diff --git a/doc/how_to_build_bsd.md b/doc/how_to_build_bsd.md
index 2c56fec..162da27 100644
--- a/doc/how_to_build_bsd.md
+++ b/doc/how_to_build_bsd.md
@@ -1,4 +1,4 @@
-# Setting up the development environment for BSD operatings systems such as NetBSD, FreeBSD, Dragonfly BSD, or OpenBSD
+# Setting up the development environment for BSD operating systems such as NetBSD, FreeBSD, Dragonfly BSD, or OpenBSD
 
 ## Required software
 
diff --git a/toonz/sources/common/tapptools/tcolorutils.cpp b/toonz/sources/common/tapptools/tcolorutils.cpp
index bc0ac37..7395124 100644
--- a/toonz/sources/common/tapptools/tcolorutils.cpp
+++ b/toonz/sources/common/tapptools/tcolorutils.cpp
@@ -1040,7 +1040,7 @@ void TColorUtils::buildColorChipPalette(QList<QPair<TPixel32, TPoint>> &palette,
 
   QList<ColorChip> colorChips;
 
-  // make rectangles by serching in the corner points
+  // make rectangles by searching in the corner points
   for (int ep0 = 0; ep0 < edgePoints.size(); ep0++) {
     QMap<EdgePoint::QUADRANT, int> corners;
 
diff --git a/toonz/sources/common/traster/traster.cpp b/toonz/sources/common/traster/traster.cpp
index 480f148..718f432 100644
--- a/toonz/sources/common/traster/traster.cpp
+++ b/toonz/sources/common/traster/traster.cpp
@@ -65,7 +65,7 @@ m_buffer = BigMemoryManager.getMemoryChunk(lx*ly*pixelSize, this);
 //m_buffer = new UCHAR[lx*ly*pixelSize];
 m_totalMemory += ((lx*ly*pixelSize)>>10);
 #ifdef _WIN32
-MessageBox( NULL, "Run out of contiguous phisical memory: please save all and
+MessageBox( NULL, "Run out of contiguous physical memory: please save all and
 restart toonz!", "Warning", MB_OK);
 #endif
 }*/
diff --git a/toonz/sources/common/trop/tresample.cpp b/toonz/sources/common/trop/tresample.cpp
index 830aa72..fd92cc7 100644
--- a/toonz/sources/common/trop/tresample.cpp
+++ b/toonz/sources/common/trop/tresample.cpp
@@ -3059,7 +3059,7 @@ void do_resample(TRasterCM32P rout, const TRasterCM32P &rin,
                v * wrapin;  // Take the associated input pixel pointer
       tcm[0] = in_tcm[0];
       if (u < lu - 1 && v < lv - 1) {
-        // Also take their 4 next neighbours (we shall perform a kinf of bilinear
+        // Also take their 4 next neighbours (we shall perform a kind of bilinear
         // interpolation)
         tcm[1] = in_tcm[1];
         tcm[2] = in_tcm[wrapin];
diff --git a/toonz/sources/image/tzl/tiio_tzl.cpp b/toonz/sources/image/tzl/tiio_tzl.cpp
index b944dc7..e375e5c 100644
--- a/toonz/sources/image/tzl/tiio_tzl.cpp
+++ b/toonz/sources/image/tzl/tiio_tzl.cpp
@@ -696,14 +696,14 @@ void TLevelWriterTzl::writeHeader(const TDimension &size) {
   assert(m_frameCountPos == 8 + CREATOR_LENGTH + 3 * sizeof(TINT32));
 
   // I put the place for the frameCount, which I will write in this position at
-  // the end  (see in the distructor)
+  // the end  (see in the destructor)
   tfwrite(&intval, 1, m_chan);
   // I put the place for the offsetTableOffset, which I will write in this
-  // position at the end  (see in the distructor)
+  // position at the end  (see in the destructor)
   intval = 0;
   tfwrite(&intval, 1, m_chan);
   // I put the place for the iconOffsetTableOffset, which I will write in this
-  // position at the end  (see in the distructor)
+  // position at the end  (see in the destructor)
   tfwrite(&intval, 1, m_chan);
   tfwrite(codec, codecLen, m_chan);
 }
diff --git a/toonz/sources/include/tcg/list.h b/toonz/sources/include/tcg/list.h
index 3af056d..43ef89e 100644
--- a/toonz/sources/include/tcg/list.h
+++ b/toonz/sources/include/tcg/list.h
@@ -574,7 +574,7 @@ course,
               \par Features
               \li  Insertion indexes are automatically generated keys with the
 same
-                   access time of the undelying container (typically super-fast
+                   access time of the underlying container (typically super-fast
                    \p O(1)).
               \li  Stable indexes and iterators with respect to <I>every
 operation</I>.
diff --git a/toonz/sources/include/toonz/childstack.h b/toonz/sources/include/toonz/childstack.h
index 5ab6ca9..6ce9145 100644
--- a/toonz/sources/include/toonz/childstack.h
+++ b/toonz/sources/include/toonz/childstack.h
@@ -97,7 +97,7 @@ Return a pointer to current xsheet.
 */
   TXsheet *getXsheet() const { return m_xsheet; }
 
-  // NON USARE. Serve solo per un truccaccio sporchissimo in
+  // DO NOT USE. It's just for a very dirty make up in
   // xshcolumnselection.cpp
   void setXsheet(TXsheet *xsheet) { m_xsheet = xsheet; }
 
diff --git a/toonz/sources/stdfx/igs_math_random.h b/toonz/sources/stdfx/igs_math_random.h
index 94ee57d..d447771 100644
--- a/toonz/sources/stdfx/igs_math_random.h
+++ b/toonz/sources/stdfx/igs_math_random.h
@@ -8,7 +8,7 @@
 2001-04-25 update
 2001-06-19 rename to 'calculator_random_plus_long.h'
 2005-02-03 rename to 'ptbl_random.h'
-2005-02-10 separete to 'ptbl_random.h' and 'ptbl_random.cxx'
+2005-02-10 separate to 'ptbl_random.h' and 'ptbl_random.cxx'
 解説 (2005-02-03.thu wrote)
 疑似乱数整数列発生関数rand()は処理系定義であるため、
 たとえば、radhat9とWindowsとでは疑似乱数列が違う。
diff --git a/toonz/sources/stdfx/iwa_motionblurfx.cpp b/toonz/sources/stdfx/iwa_motionblurfx.cpp
index b29a588..3b62aa4 100644
--- a/toonz/sources/stdfx/iwa_motionblurfx.cpp
+++ b/toonz/sources/stdfx/iwa_motionblurfx.cpp
@@ -583,7 +583,7 @@ void Iwa_MotionBlurCompFx::composeBackgroundExposure_CPU(
       bgExposure.y *= (*bg_p).w;
       bgExposure.z *= (*bg_p).w;
 
-      /* Over composte with front layers */
+      /* Over composite with front layers */
       (*out_p).x = (*out_p).x + bgExposure.x * (1.0f - (*out_p).w);
       (*out_p).y = (*out_p).y + bgExposure.y * (1.0f - (*out_p).w);
       (*out_p).z = (*out_p).z + bgExposure.z * (1.0f - (*out_p).w);
diff --git a/toonz/sources/stdfx/iwa_rainbow_intensity.h b/toonz/sources/stdfx/iwa_rainbow_intensity.h
index 7c43459..1bf8120 100644
--- a/toonz/sources/stdfx/iwa_rainbow_intensity.h
+++ b/toonz/sources/stdfx/iwa_rainbow_intensity.h
@@ -2,7 +2,7 @@
 
 #ifndef RAINBOW_INTENSITY_H
 #define RAINBOW_INTENSITY_H
-// Scattering Intensity from water droplet for each wavelengh
+// Scattering Intensity from water droplet for each wavelength
 // and scattering angle
 // Numerical computation is done with MiePlot by Philip Laven
 // Parameters
diff --git a/toonz/sources/stdfx/iwa_soapbubblefx.cpp b/toonz/sources/stdfx/iwa_soapbubblefx.cpp
index 5a2eccf..ecf1bd7 100644
--- a/toonz/sources/stdfx/iwa_soapbubblefx.cpp
+++ b/toonz/sources/stdfx/iwa_soapbubblefx.cpp
@@ -627,7 +627,7 @@ void Iwa_SoapBubbleFx::do_createBlurFilter(float* dst_p, int size,
       if (length2 >= radius2)
         *tmp_p = 0.0f;
       else {
-        /* normalize distace from the filter center, to 0-1 */
+        /* normalize distance from the filter center, to 0-1 */
         *tmp_p = 1.0f - std::sqrt(length2) / radius;
         sum += *tmp_p;
       }
diff --git a/toonz/sources/stdfx/iwa_soapbubblefx.h b/toonz/sources/stdfx/iwa_soapbubblefx.h
index baf72a5..c2a9b59 100644
--- a/toonz/sources/stdfx/iwa_soapbubblefx.h
+++ b/toonz/sources/stdfx/iwa_soapbubblefx.h
@@ -67,7 +67,7 @@ protected:
 
   void do_createBlurFilter(float* dst_p, int size, float radius);
 
-  void do_applyFilter(float* depth_map_p, TDimensionI dim, float* distace_p,
+  void do_applyFilter(float* depth_map_p, TDimensionI dim, float* distance_p,
                       USHORT* binarized_p, float* blur_filter_p,
                       int blur_filter_size, double frame,
                       const TRenderSettings& settings);
diff --git a/toonz/sources/toonz/ObjectTracker.cpp b/toonz/sources/toonz/ObjectTracker.cpp
index 4765b19..bd9270a 100644
--- a/toonz/sources/toonz/ObjectTracker.cpp
+++ b/toonz/sources/toonz/ObjectTracker.cpp
@@ -66,7 +66,7 @@ CObjectTracker::CObjectTracker(int imW, int imH, bool _colorimage,
 };
 
 //--------------------------------------------------------------------------------------------------------
-// Distructor
+// Destructor
 CObjectTracker::~CObjectTracker() {}
 
 //--------------------------------------------------------------------------------------------------------
diff --git a/toonz/sources/toonz/cellkeyframeselection.cpp b/toonz/sources/toonz/cellkeyframeselection.cpp
index 44a9620..23844fa 100644
--- a/toonz/sources/toonz/cellkeyframeselection.cpp
+++ b/toonz/sources/toonz/cellkeyframeselection.cpp
@@ -76,7 +76,7 @@ void TCellKeyframeSelection::copyCellsKeyframes() {
                                startPos);
     data->setKeyframeData(keyframeData);
   }
-  // Set the cliboard
+  // Set the clipboard
   QClipboard *clipboard = QApplication::clipboard();
   clipboard->setMimeData(data, QClipboard::Clipboard);
 }
diff --git a/toonz/sources/toonz/cellselection.cpp b/toonz/sources/toonz/cellselection.cpp
index c55ba8b..1f648ab 100644
--- a/toonz/sources/toonz/cellselection.cpp
+++ b/toonz/sources/toonz/cellselection.cpp
@@ -3038,7 +3038,7 @@ void TCellSelection::overWritePasteCells() {
     TCellData *beforeData = new TCellData();
     beforeData->setCells(xsh, r0, c0, r1, c1);
 
-    /*-- InsertをFalseにすることで、Ovewriteペーストになる
+    /*-- InsertをFalseにすることで、Overwriteペーストになる
             r1,c1はペースト範囲にあわせリサイズされる
     --*/
     bool isPaste = pasteCellsWithoutUndo(r0, c0, r1, c1, false);
diff --git a/toonz/sources/toonz/drawingdata.cpp b/toonz/sources/toonz/drawingdata.cpp
index 5698eb9..afcc099 100644
--- a/toonz/sources/toonz/drawingdata.cpp
+++ b/toonz/sources/toonz/drawingdata.cpp
@@ -452,7 +452,7 @@ DrawingData::~DrawingData() {
 
 void DrawingData::releaseData() {
   // do it when you're sure you no t need images anymore... (for example in an
-  // undo distructor)
+  // undo destructor)
   // int i;
   // for(i=0; i<m_imageSet.size(); i++)
   //  TImageCache::instance()->remove(m_imageSet[i]);
diff --git a/toonz/sources/toonz/dvdirtreeview.cpp b/toonz/sources/toonz/dvdirtreeview.cpp
index 7366a35..18ff154 100644
--- a/toonz/sources/toonz/dvdirtreeview.cpp
+++ b/toonz/sources/toonz/dvdirtreeview.cpp
@@ -1625,7 +1625,7 @@ void DvDirTreeView::getExpandedPathsRecursive(const QModelIndex &index,
       paths.append(path);
     }
   }
-  /*- serch child nodes if this node is expanded -*/
+  /*- search child nodes if this node is expanded -*/
   if (index != rootIndex() && !isExpanded(index)) return;
 
   int count = DvDirModel::instance()->rowCount(index);
diff --git a/toonz/sources/toonz/exportxsheetpdf.cpp b/toonz/sources/toonz/exportxsheetpdf.cpp
index 4b95abb..8f1e018 100644
--- a/toonz/sources/toonz/exportxsheetpdf.cpp
+++ b/toonz/sources/toonz/exportxsheetpdf.cpp
@@ -2579,7 +2579,7 @@ void ExportXsheetPdfPopup::onExport() {
         tr("The file %1 already exists.\nDo you want to overwrite it?")
             .arg(fp.getQString());
     int ret =
-        DVGui::MsgBox(question, QObject::tr("Ovewrite"), QObject::tr("Cancel"));
+        DVGui::MsgBox(question, QObject::tr("Overwrite"), QObject::tr("Cancel"));
     if (ret == 0 || ret == 2) {
       return;
     }
@@ -2649,7 +2649,7 @@ void ExportXsheetPdfPopup::onExportPNG() {
         tr("The file %1 already exists.\nDo you want to overwrite it?")
             .arg(fp.getQString());
     int ret =
-        DVGui::MsgBox(question, QObject::tr("Ovewrite"), QObject::tr("Cancel"));
+        DVGui::MsgBox(question, QObject::tr("Overwrite"), QObject::tr("Cancel"));
     if (ret == 0 || ret == 2) {
       return;
     }
diff --git a/toonz/sources/toonz/filebrowser.cpp b/toonz/sources/toonz/filebrowser.cpp
index c583554..c4d1460 100644
--- a/toonz/sources/toonz/filebrowser.cpp
+++ b/toonz/sources/toonz/filebrowser.cpp
@@ -338,7 +338,7 @@ void FileBrowser::storeFolderHistory() {
     m_indexHistoryList << currentModelIndex;
     m_currentPosition++;
   }
-  // If the next hitory item is the same as the current one, just move to it
+  // If the next history item is the same as the current one, just move to it
   else if (m_indexHistoryList[m_currentPosition + 1] == currentModelIndex) {
     m_currentPosition++;
   }
@@ -536,7 +536,7 @@ void FileBrowser::refreshCurrentFolderItems() {
   if (parentFp != TFilePath("") && parentFp != m_folder)
     m_items.push_back(Item(parentFp, true, false));
 
-  // register the all folder items by using the folde tree model
+  // register all folder items by using the folder tree model
   DvDirModel *model        = DvDirModel::instance();
   QModelIndex currentIndex = model->getIndexByPath(m_folder);
   if (currentIndex.isValid()) {
diff --git a/toonz/sources/toonz/flipbook.cpp b/toonz/sources/toonz/flipbook.cpp
index ac550ac..ddb542b 100644
--- a/toonz/sources/toonz/flipbook.cpp
+++ b/toonz/sources/toonz/flipbook.cpp
@@ -1210,7 +1210,7 @@ void FlipBook::setLevel(const TFilePath &fp, TPalette *palette, int from,
                                  m_framesCount);                         // to
       }
 
-      // An old archived bug says that simulatenous open for read of the same
+      // An old archived bug says that simultaneous open for read of the same
       // tlv are not allowed...
       // if(m_lr && m_lr->getFilePath().getType()=="tlv")
       //  m_lr = TLevelReaderP();
@@ -1644,7 +1644,7 @@ TImageP FlipBook::getCurrentImage(int frame) {
       m_loadboxes[id] = showSub ? m_loadbox : TRect();
     }
 
-    // An old archived bug says that simulatenous open for read of the same tlv
+    // An old archived bug says that simultaneous open for read of the same tlv
     // are not allowed...
     // if(fp.getType()=="tlv")
     //  m_lr = TLevelReaderP();
diff --git a/toonz/sources/toonz/iocommand.cpp b/toonz/sources/toonz/iocommand.cpp
index 43a6550..e285611 100644
--- a/toonz/sources/toonz/iocommand.cpp
+++ b/toonz/sources/toonz/iocommand.cpp
@@ -3064,7 +3064,7 @@ public:
     int ret;
     if (sl && sl->getPath().getType() == "pli") {
       question = "Saving " + toQString(palettePath) +
-                 "\nThis command will ovewrite the level data as well.  Are "
+                 "\nThis command will overwrite the level data as well.  Are "
                  "you sure ?";
       ret =
           DVGui::MsgBox(question, QObject::tr("OK"), QObject::tr("Cancel"), 0);
diff --git a/toonz/sources/toonz/previewer.cpp b/toonz/sources/toonz/previewer.cpp
index 8dbafd8..bc96311 100644
--- a/toonz/sources/toonz/previewer.cpp
+++ b/toonz/sources/toonz/previewer.cpp
@@ -352,7 +352,7 @@ void Previewer::Imp::updateRenderSettings() {
   else
     renderSettings.m_shrinkY = renderSettings.m_shrinkX = 1;
 
-  // In case the settings changee, erase all previously cached images
+  // In case the settings changed, erase all previously cached images
   if (renderSettings != m_renderSettings) {
     m_renderSettings = renderSettings;
 
diff --git a/toonz/sources/toonz/xshcolumnviewer.cpp b/toonz/sources/toonz/xshcolumnviewer.cpp
index 09d833b..1a09ff1 100644
--- a/toonz/sources/toonz/xshcolumnviewer.cpp
+++ b/toonz/sources/toonz/xshcolumnviewer.cpp
@@ -1122,7 +1122,7 @@ void ColumnArea::DrawHeader::drawThumbnail(QPixmap &iconPixmap) const {
                                                : PredefinedRect::THUMBNAIL)
                                  .translated(orig);
 
-  // pallete thumbnail
+  // palette thumbnail
   if (column->getPaletteColumn()) {
     p.drawPixmap(thumbnailImageRect, iconPixmap);
     return;
diff --git a/toonz/sources/toonz/xsheetviewer.h b/toonz/sources/toonz/xsheetviewer.h
index 18090e7..af8ee07 100644
--- a/toonz/sources/toonz/xsheetviewer.h
+++ b/toonz/sources/toonz/xsheetviewer.h
@@ -191,7 +191,7 @@ class XsheetViewer final : public QFrame, public SaveLoadQSettings {
 
   QColor m_lightLightBgColor;
   QColor m_lightBgColor;
-  QColor m_bgColor;  // row area backgroound
+  QColor m_bgColor;  // row area background
   QColor m_darkBgColor;
   QColor m_lightLineColor;  // horizontal lines (146,144,146)
   QColor m_darkLineColor;
diff --git a/toonz/sources/toonz/xshrowviewer.h b/toonz/sources/toonz/xshrowviewer.h
index b74912d..e69c915 100644
--- a/toonz/sources/toonz/xshrowviewer.h
+++ b/toonz/sources/toonz/xshrowviewer.h
@@ -64,7 +64,7 @@ class RowArea final : public QWidget {
 
   // Return when the item-menu setAutoMarkers can be enabled.
   bool canSetAutoMarkers();
-  // Return the number of the last non-empty cell finded. You can set the
+  // Return the number of the last non-empty cell found. You can set the
   // direction of the search.
   int getNonEmptyCell(int row, int column, Direction);
 
diff --git a/toonz/sources/toonzlib/Naa2TlvConverter.cpp b/toonz/sources/toonzlib/Naa2TlvConverter.cpp
index d3ff867..45c90b1 100644
--- a/toonz/sources/toonzlib/Naa2TlvConverter.cpp
+++ b/toonz/sources/toonzlib/Naa2TlvConverter.cpp
@@ -733,7 +733,7 @@ void Naa2TlvConverter::assignColorTypes() {
 
 //-----------------------------------------------------------------------------
 
-void Naa2TlvConverter::addBorderInks()  // add syntethic inks: lines between two
+void Naa2TlvConverter::addBorderInks()  // add synthetic inks: lines between two
                                         // adjacent fill-regions
 {
   int lx                   = m_regionRas->getLx();
diff --git a/toonz/sources/toonzlib/ikjacobian.cpp b/toonz/sources/toonzlib/ikjacobian.cpp
index 091801c..cd311fe 100644
--- a/toonz/sources/toonzlib/ikjacobian.cpp
+++ b/toonz/sources/toonzlib/ikjacobian.cpp
@@ -269,7 +269,7 @@ MatrixRmn &MatrixRmn::AddToDiagonal(double d)  // Adds d to each diagonal entry
   return *this;
 }
 
-// Aggiunge i temini del vettore alla diagonale
+// Adds the terms of the vector to the diagonal
 MatrixRmn &MatrixRmn::AddToDiagonal(
     const VectorRn &v)  // Adds d to each diagonal entry
 {
diff --git a/toonz/sources/toonzqt/flipconsole.cpp b/toonz/sources/toonzqt/flipconsole.cpp
index 6b15593..f8bca51 100644
--- a/toonz/sources/toonzqt/flipconsole.cpp
+++ b/toonz/sources/toonzqt/flipconsole.cpp
@@ -177,7 +177,7 @@ void PlaybackExecutor::run() {
       1000000000 / (qint64)abs(m_fps);  // User-required time between frames
 
   qint64 emissionInstant = 0;  // starting instant in which rendering is invoked
-  qint64 avgSwapTime     = 0;  // average time for swapping bufers
+  qint64 avgSwapTime     = 0;  // average time for swapping buffers
   qint64 shortTermDelayAdjuster =
       0;  // accumurate recent errors and adjust in short term
 
@@ -203,7 +203,7 @@ void PlaybackExecutor::run() {
         avgSwapTime += avgSwapTimeD;
       avgSwapTime = std::min(targetFrameTime, std::max(avgSwapTime, (qint64)0));
 
-      // preapre for the next sampling
+      // prepare for the next sampling
       lastFrameCounts[currSample]    = playedFramesCount;
       lastSampleInstants[currSample] = emissionInstant;
       currSample                     = (currSample + 1) % 4;