diff --git a/toonz/sources/common/tgeometry/tcurveutil.cpp b/toonz/sources/common/tgeometry/tcurveutil.cpp
index 42c7bbc..494929a 100644
--- a/toonz/sources/common/tgeometry/tcurveutil.cpp
+++ b/toonz/sources/common/tgeometry/tcurveutil.cpp
@@ -472,7 +472,7 @@ double tdistance(const TSegment &segment, const TPointD &point) {
 
 //-----------------------------------------------------------------------------
 /*
-This formule is derived from Graphic Gems pag. 600
+This formula is derived from Graphic Gems pag. 600
 
   e = h^2 |a|/8
 
diff --git a/toonz/sources/common/trop/tantialias.cpp b/toonz/sources/common/trop/tantialias.cpp
index 3ccce3b..6ada184 100644
--- a/toonz/sources/common/trop/tantialias.cpp
+++ b/toonz/sources/common/trop/tantialias.cpp
@@ -134,7 +134,7 @@ inline bool checkNeighbourHood(int x, int y, PIX *pix, int lx, int ly, int dx,
 
   // Connect by minority: if there are more pixels like those on the 00-11
   // diagonal, connect the other,
-  // and viceversa.
+  // and vice versa.
   return count1 > count2;
 }
 }
diff --git a/toonz/sources/common/tvectorimage/outlineApproximation.cpp b/toonz/sources/common/tvectorimage/outlineApproximation.cpp
index 9ab70b0..ce0727e 100644
--- a/toonz/sources/common/tvectorimage/outlineApproximation.cpp
+++ b/toonz/sources/common/tvectorimage/outlineApproximation.cpp
@@ -35,7 +35,7 @@ class notValidOutline {};
 namespace {
 
 /*
-  This formule is derived from Graphic Gems pag. 600
+  This formula is derived from Graphic Gems pag. 600
 
     e = h^2 |a|/8
 
diff --git a/toonz/sources/common/tvrender/tfont_qt.cpp b/toonz/sources/common/tvrender/tfont_qt.cpp
index 58b3450..4ce4e01 100644
--- a/toonz/sources/common/tvrender/tfont_qt.cpp
+++ b/toonz/sources/common/tvrender/tfont_qt.cpp
@@ -171,8 +171,8 @@ TPoint TFont::drawChar(QImage &outImage, TPoint &unused, wchar_t charcode,
   // alphaMapForGlyph with a space character returns an invalid
   // QImage for some reason.
   // Bug 3604: https://github.com/opentoonz/opentoonz/issues/3604
-  // (21/1/2022) Use this workaround for all platforms as the crash also occured
-  // in windows when the display is scaled up.
+  // (21/1/2022) Use this workaround for all platforms as the crash also
+  // occurred in windows when the display is scaled up.
   if (chars[0].isSpace()) {
     int w = QFontMetrics(m_pimpl->m_font).horizontalAdvance(chars[0]);
     outImage =
diff --git a/toonz/sources/image/avi/tiio_avi.cpp b/toonz/sources/image/avi/tiio_avi.cpp
index 6e40cff..c53558a 100644
--- a/toonz/sources/image/avi/tiio_avi.cpp
+++ b/toonz/sources/image/avi/tiio_avi.cpp
@@ -971,15 +971,15 @@ int TLevelReaderAvi::readFrameFromStream(void *bufferOut, DWORD &bufferSize,
                                          int frameIndex) const {
   assert(bufferOut && bufferSize > 0);
   LONG bytesReaded   = 0;
-  LONG samplesReaded = 0;
+  LONG samplesRead = 0;
 
   int rc = AVIStreamRead(m_videoStream, frameIndex, 1, bufferOut, bufferSize,
-                         &bytesReaded, &samplesReaded);
+                         &bytesReaded, &samplesRead);
   if (!rc) {
-    assert(samplesReaded == 1);  // deve aver letto un frame!!!
+    assert(samplesRead == 1);  // must have read a frame!!!
     assert(bytesReaded <=
-           (LONG)bufferSize);  // deve aver letto un numero di byte
-    // minore o uguale di quello che ci aspettiamo
+           (LONG)bufferSize);  // must have read a number of bytes
+    // less than or equal to what we expect
     bufferSize = bytesReaded;
   }
   return rc;
diff --git a/toonz/sources/image/tzl/tiio_tzl.cpp b/toonz/sources/image/tzl/tiio_tzl.cpp
index e375e5c..9dc177d 100644
--- a/toonz/sources/image/tzl/tiio_tzl.cpp
+++ b/toonz/sources/image/tzl/tiio_tzl.cpp
@@ -103,13 +103,13 @@ static int tfwrite(double *data, unsigned int count, FILE *f) {
 
 namespace {
 
-bool erasedFrame;  // Vera se è stato rimosso almeno un frame.
+bool erasedFrame;  // True if at least one frame has been removed.
 
 bool writeVersionAndCreator(FILE *chan, const char *version, QString creator) {
   if (!chan) return false;
   tfwrite(version, strlen(version), chan);
 
-  // creator : CREATOR_LENGTH characater
+  // creator : CREATOR_LENGTH character
   char s[CREATOR_LENGTH];
   if (creator.length() == 0) creator = "UNKNOWN";
   memset(s, 0, sizeof s);
@@ -1206,11 +1206,11 @@ void TLevelWriterTzl::createIcon(const TImageP &imgIn, TImageP &imgOut) {
   if (!TRect(m_iconSize).contains(savebox))  // it should be better to use
                                              // tfloor instead of tround in the
                                              // previous lines:
-    // sometimes, for rounding problems, the savebox is outside 1 pixel the
+    // sometimes, for rounding problems, the savebox is outside the 1 pixel
     // raster size.
     // the best solution should be to replace tround with tfloor here
     // and in the icon reading of tzl 1.4 (method load14),
-    // but this way the old 1.4 tzl are not readed correctly (crash!)
+    // but this way the old 1.4 tzl are not read correctly (crash!)
     // so, this 'if' is a patch. vinz
     savebox = savebox * TRect(m_iconSize);
   thumbnailRas->clearOutside(savebox);
@@ -1328,7 +1328,7 @@ bool TLevelWriterTzl::resizeIcons(const TDimension &newSize) {
   if (!m_chan) return false;
   assert(m_version >= 13);
 
-  // faccio una copia di m_path per poi usarla per la resizeIcons()
+  // make a copy of m_path to be able to use it for resizeIcons()
   fclose(m_chan);
   m_chan = 0;
   TFileStatus fs(m_path);
@@ -1566,7 +1566,7 @@ bool TLevelReaderTzl::getIconSize(TDimension &iconSize) {
   fread(&iconLx, sizeof(TINT32), 1, m_chan);
   fread(&iconLy, sizeof(TINT32), 1, m_chan);
   assert(iconLx > 0 && iconLy > 0);
-  // ritorno alla posizione corrente
+  // return to the current position
   fseek(m_chan, currentPos, SEEK_SET);
   iconSize = TDimension(iconLx, iconLy);
   return true;
@@ -2054,7 +2054,7 @@ static TRect applyShrinkAndRegion(TRasterP &ras, int shrink, TRect region,
   if (shrink > 1) {
     ras = TRop::shrink(ras, shrink);
   }
-  // calcolo la nuova savebox
+  // calculate the new savebox
   savebox *= region;
   if (savebox == TRect() || savebox.getLx() <= 0 || savebox.getLy() <= 0)
     return TRect();
@@ -2359,7 +2359,7 @@ TImageP TImageReaderTzl::load() {
         ras->clear();
         savebox = m_region;
       } else {
-        // se sia la savebox che la regione sono vuote non faccio nulla
+        // if both the savebox and the region are empty, do nothing
       }
     }
     ti->setCMapped(ras);
diff --git a/toonz/sources/include/ext/plasticdeformerstorage.h b/toonz/sources/include/ext/plasticdeformerstorage.h
index cef230e..a39f680 100644
--- a/toonz/sources/include/ext/plasticdeformerstorage.h
+++ b/toonz/sources/include/ext/plasticdeformerstorage.h
@@ -149,7 +149,7 @@ deform-related
   Cached data is uniquely associated with pairs of meshImage and deformed
 skeletons,
   meaning that the same meshImage can be deformed by multiple skeletons, and
-viceversa.
+vice versa.
   \n\n
   A deformer data request needs an affine transform in input, which is intended
 to
diff --git a/toonz/sources/include/tregion.h b/toonz/sources/include/tregion.h
index f2ae4c9..0decd68 100644
--- a/toonz/sources/include/tregion.h
+++ b/toonz/sources/include/tregion.h
@@ -244,7 +244,7 @@ public:
 };
 
 //-----------------------------------------------------------------------------
-/*Spostata in tregion.cpp
+/* Moved to tregion.cpp
 inline int TRegion::getStyle() const
 {
 int ret = 0;
@@ -271,10 +271,10 @@ public:
   virtual void update(const TPointD &p1, const TPointD &p2) = 0;
 };
 
-// permette di calcolare varie grandesse sul poligono della regione,
-// come l'area, il baricentro, il perimetro...
-// per usarla si deve sottoclassare la classe virtuale TRegionFeatureFormula
-// specificando la formual della grandezza da calcolare.
+// allows you to calculate various measurements on the polygon
+// of the region, such as area, center of mass, perimeter...
+// to use it, you must subclass the virtual class by specifying
+// the formula of the measurement to be calculated.
 
 void DVAPI computeRegionFeature(const TRegion &r,
                                 TRegionFeatureFormula &formula);
diff --git a/toonz/sources/include/trenderresourcemanager.h b/toonz/sources/include/trenderresourcemanager.h
index 9b0f3da..bf4d91d 100644
--- a/toonz/sources/include/trenderresourcemanager.h
+++ b/toonz/sources/include/trenderresourcemanager.h
@@ -171,7 +171,7 @@ A variation of the MANAGER_FILESCOPE_DECLARATION macro used to declare
 dependencies between
 resource managers. A manager always receives start notifications \a after those
 from which
-it depends, and viceversa for end notifications. The same applies for
+it depends, and vice versa for end notifications. The same applies for
 constructors and destructors.
 \n \n
 The dependencies declarations list is a sequence of static \c
diff --git a/toonz/sources/include/tsound_t.h b/toonz/sources/include/tsound_t.h
index 42b99bd..8adedf0 100644
--- a/toonz/sources/include/tsound_t.h
+++ b/toonz/sources/include/tsound_t.h
@@ -135,7 +135,7 @@ from which it's created. It has no reference to the object.
 
   //----------------------------------------------------------------------------
 
-  //! Applies a transformation (echo, reverb, ect) to the object and returns the
+  //! Applies a transformation (echo, reverb, etc) to the object and returns the
   //! transformed soundtrack
   TSoundTrackP apply(TSoundTransform *transform) override;
   //----------------------------------------------------------------------------
diff --git a/toonz/sources/include/tspectrum.h b/toonz/sources/include/tspectrum.h
index 6e350fa..f48174a 100644
--- a/toonz/sources/include/tspectrum.h
+++ b/toonz/sources/include/tspectrum.h
@@ -41,7 +41,7 @@ private:
                          ColorKey(s, T()),
                          [](const ColorKey &a, const ColorKey &b) {
                            return a.first < b.first;
-                         });  // compare only key postions
+                         });  // compare only key positions
 
     if (b == m_sortedKeys.end())
       return m_sortedKeys.rbegin()->second;
diff --git a/toonz/sources/stdfx/iwa_fractalnoisefx.cpp b/toonz/sources/stdfx/iwa_fractalnoisefx.cpp
index 486170c..5716690 100644
--- a/toonz/sources/stdfx/iwa_fractalnoisefx.cpp
+++ b/toonz/sources/stdfx/iwa_fractalnoisefx.cpp
@@ -324,7 +324,7 @@ void Iwa_FractalNoiseFx::doCompute(TTile &tile, double frame,
               // line of sight
               TPointD _p = TTranslation(tile.m_pos) * TPointD(x, y);
               // offset by combination of offsets of A) projection position and
-              // B) eye positon.
+              // B) eye position.
               //
               // A) 0.5 * projection position offset
               QVector3D p(_p.x - center.x * 0.5, _p.y - center.y * 0.5, 0.0);
diff --git a/toonz/sources/tnztools/plastictool.cpp b/toonz/sources/tnztools/plastictool.cpp
index 9787069..be85dca 100644
--- a/toonz/sources/tnztools/plastictool.cpp
+++ b/toonz/sources/tnztools/plastictool.cpp
@@ -887,7 +887,7 @@ void PlasticTool::onColumnSwitched() {
 void PlasticTool::onXsheetChanged() {
   onColumnSwitched();
   TTool::updateEnabled();  // Current cell may no longer be a mesh one (or
-                           // viceversa),
+                           // vice versa),
 }  // so tool enabled status must be updated.
 
 //------------------------------------------------------------------------
diff --git a/toonz/sources/tnztools/toolutils.cpp b/toonz/sources/tnztools/toolutils.cpp
index 674ee00..45ebc40 100644
--- a/toonz/sources/tnztools/toolutils.cpp
+++ b/toonz/sources/tnztools/toolutils.cpp
@@ -1485,7 +1485,7 @@ double ToolUtils::ConeSubVolume::compute(double cover) {
   if (i == 20)
     return m_values[i];
   else
-    // Interpolazione lineare.
+    // Linear interpolation.
     return (-(x - (i + 1)) * m_values[i]) - (-(x - i) * m_values[i + 1]);
 }
 
@@ -1607,14 +1607,14 @@ void ToolUtils::drawBalloon(const TPointD &pos, std::string text,
   pp.moveTo(x0, y - 8 * devPixRatio);
   pp.lineTo(0, y + delta.y);
   pp.lineTo(x0, y);
-  /* bordi arrotondati
+  /* rounded edges
   int arcSize = 10;
   pp.arcTo(x0,y1-arcSize,arcSize,arcSize,180,90);
   pp.arcTo(x1-arcSize,y1-arcSize,arcSize,arcSize,270,90);
   pp.arcTo(x1-arcSize,y0,arcSize,arcSize,0,90);
   pp.arcTo(x0,y0,arcSize,arcSize,90,90);
   */
-  // bordi acuti
+  // sharp edges
   pp.lineTo(x0, y1);
   pp.lineTo(x1, y1);
   pp.lineTo(x1, y0);
diff --git a/toonz/sources/toonz/castviewer.cpp b/toonz/sources/toonz/castviewer.cpp
index ec71d72..68831ca 100644
--- a/toonz/sources/toonz/castviewer.cpp
+++ b/toonz/sources/toonz/castviewer.cpp
@@ -167,7 +167,7 @@ void CastTreeViewer::enableCommands() {
 
 void CastTreeViewer::onFolderChanged(QTreeWidgetItem *current,
                                      QTreeWidgetItem *previous) {
-  // rende la selezione corrente; serve per intercettare il comando MI_Clear
+  // makes the selection current; serves to intercept the MI_Clear command
   makeCurrent();
 }
 
@@ -728,7 +728,7 @@ QMenu *CastBrowser::getContextMenu(QWidget *parent, int index) {
   for (it = indices.begin(); it != indices.end(); ++it) {
     int index = *it;
     if (index < 0 || index >= m_castItems->getItemCount())
-      continue;  // non dovrebbe mai succedere
+      continue;  // should never happen
     TXshSimpleLevel *sl = m_castItems->getItem(index)->getSimpleLevel();
     if (!sl) {
       if (m_castItems->getItem(index)->getPaletteLevel())
@@ -762,7 +762,7 @@ QMenu *CastBrowser::getContextMenu(QWidget *parent, int index) {
     menu->addAction(cm->getAction(MI_EditLevel));
   if (!paletteSelected) menu->addAction(cm->getAction(MI_SaveLevel));
   menu->addSeparator();
-  // MI_ConvertToVectors se sono stati selezionati solo livelli non vettoriali
+  // MI_ConvertToVectors if only non-vector layers were selected
   if (!audioSelected && !paletteSelected && !vectorLevelSelected)
     menu->addAction(cm->getAction(MI_ConvertToVectors));
   menu->addSeparator();
diff --git a/toonz/sources/toonz/sceneviewer.cpp b/toonz/sources/toonz/sceneviewer.cpp
index 40fd9d6..5a926a5 100644
--- a/toonz/sources/toonz/sceneviewer.cpp
+++ b/toonz/sources/toonz/sceneviewer.cpp
@@ -1025,7 +1025,7 @@ void SceneViewer::showEvent(QShowEvent *) {
   m_visualSettings.m_sceneProperties =
       TApp::instance()->getCurrentScene()->getScene()->getProperties();
 
-  // Se il viewer e' show e il preview e' attivo aggiungo il listner al preview
+  // If the viewer is hidden and preview is activated, remove the listener from preview
   if (m_previewMode != NO_PREVIEW)
     Previewer::instance(m_previewMode == SUBCAMERA_PREVIEW)->addListener(this);
 
@@ -1112,7 +1112,7 @@ void SceneViewer::showEvent(QShowEvent *) {
 //-----------------------------------------------------------------------------
 
 void SceneViewer::hideEvent(QHideEvent *) {
-  // Se il viewer e' hide e il preview e' attivo rimuovo il listner dal preview
+  // If the viewer is hidden and preview is activated, remove the listener from preview
   if (m_previewMode != NO_PREVIEW)
     Previewer::instance(m_previewMode == SUBCAMERA_PREVIEW)
         ->removeListener(this);
diff --git a/toonz/sources/toonzlib/fxcommand.cpp b/toonz/sources/toonzlib/fxcommand.cpp
index e661775..e30a787 100644
--- a/toonz/sources/toonzlib/fxcommand.cpp
+++ b/toonz/sources/toonzlib/fxcommand.cpp
@@ -3416,7 +3416,7 @@ void SetParentUndo::initialize() {
   if (!m_parentFx) return;
 
   // NOTE: We cannot store this directly, since it's the actual out that owns
-  // the actual in, not viceversa
+  // the actual in, not vice versa
   TFx *parentFx = ::getActualIn(m_parentFx.getPointer());
 
   TXsheet *xsh = m_xshHandle->getXsheet();
diff --git a/toonz/sources/toonzqt/docklayout.cpp b/toonz/sources/toonzqt/docklayout.cpp
index 252199f..c084318 100644
--- a/toonz/sources/toonzqt/docklayout.cpp
+++ b/toonz/sources/toonzqt/docklayout.cpp
@@ -1172,7 +1172,7 @@ bool Region::addItemSize(DockWidget *item) {
     m_maximumSize[vertical] = std::min(m_maximumSize[vertical],
                                        item->getDockedMaximumSize().height());
   } else {
-    // Viceversa
+    // Vice versa
     m_minimumSize[vertical] += item->getDockedMinimumSize().height() + sepWidth;
     m_maximumSize[vertical] += item->getDockedMaximumSize().height() + sepWidth;
 
@@ -1225,7 +1225,7 @@ bool Region::subItemSize(DockWidget *item) {
             m_maximumSize[vertical], m_childList[i]->getMaximumSize(vertical));
       }
   } else {
-    // Viceversa
+    // Vice versa
     m_minimumSize[vertical] -= item->minimumSize().height() + sepWidth;
     m_maximumSize[vertical] -= item->maximumSize().height() + sepWidth;
 
diff --git a/toonz/sources/toonzqt/styleeditor.cpp b/toonz/sources/toonzqt/styleeditor.cpp
index 654d047..6392332 100644
--- a/toonz/sources/toonzqt/styleeditor.cpp
+++ b/toonz/sources/toonzqt/styleeditor.cpp
@@ -999,7 +999,7 @@ void SquaredColorWheel::setChannel(int channel) {
 //    ColorSlider  implementation
 //*****************************************************************************
 
-// Adquire size later...
+// Acquire size later...
 int ColorSlider::s_chandle_size      = -1;
 int ColorSlider::s_chandle_tall      = -1;
 int ColorSlider::s_slider_appearance = -1;
diff --git a/toonz/sources/translations_docs/english/MaxMinIno.tex b/toonz/sources/translations_docs/english/MaxMinIno.tex
index 42e962f..234f735 100644
--- a/toonz/sources/translations_docs/english/MaxMinIno.tex
+++ b/toonz/sources/translations_docs/english/MaxMinIno.tex
@@ -39,7 +39,7 @@ Specify the processing method.\par
 \textquotedbl Min\textquotedbl \ -> Inflate the dark areas of the image\par
 When using \textquotedbl Min\textquotedbl , black lines in the cell image outline will be painted with 0\par 
 in the transparent area outside them, so transparent area expands and black lines\par 
-dissappear.\par
+disappear.\par
 It also increases the region defined by the Alpha in the same way.\par
 The default setting is \textquotedbl Max\textquotedbl .\\
 \\
diff --git a/toonz/sources/translations_docs/english/WarpHVIno.tex b/toonz/sources/translations_docs/english/WarpHVIno.tex
index 57538bd..84993b3 100644
--- a/toonz/sources/translations_docs/english/WarpHVIno.tex
+++ b/toonz/sources/translations_docs/english/WarpHVIno.tex
@@ -29,7 +29,7 @@ Connect a reference image to distort in the vertical direction.\\
 \\
 -{-}- \ Settings \ -{-}-\\
 H reference\par
-Allows to select which channel of the \textquotedbl Hori\textquotedbl \ image will drive the distorsion.\\
+Allows to select which channel of the \textquotedbl Hori\textquotedbl \ image will drive the distortion.\\
 \\
 H MaxLen\par
 Distorts the picture in the horizontal direction.\par
@@ -38,16 +38,16 @@ The unit is mm, values can range from 0 to 100.\par
 Default value is 0, which will not make any effect.\\
 \par
 8bits Image\par
-\noindent \hskip 7em \ \ \ \ 1 -MaxLen(mm) distorsion.\par
+\noindent \hskip 7em \ \ \ \ 1 -MaxLen(mm) distortion.\par
 \noindent \hskip 7em 128 no distortion.\par
-\noindent \hskip 7em 255 MaxLen(mm) distorsion.\par
+\noindent \hskip 7em 255 MaxLen(mm) distortion.\par
 16bits Image\par
-\noindent \hskip 7em \ \ \ \ \ \ \ \ 1 -MaxLen(mm) distorsion.\par
+\noindent \hskip 7em \ \ \ \ \ \ \ \ 1 -MaxLen(mm) distortion.\par
 \noindent \hskip 7em 32768 no distortion.\par
-\noindent \hskip 7em 65535 MaxLen(mm) distorsion.\\
+\noindent \hskip 7em 65535 MaxLen(mm) distortion.\\
 \\
 V reference\par
-Allows to select which channel of the \textquotedbl Vert\textquotedbl \ image will drive the distorsion.\\
+Allows to select which channel of the \textquotedbl Vert\textquotedbl \ image will drive the distortion.\\
 \\
 V MaxLen\par
 Distorts the picture in the vertical direction.\par