diff --git a/core/lib/Drupal/Component/FileSystem/FileSystem.php b/core/lib/Drupal/Component/FileSystem/FileSystem.php
index 7a1c551f2430828e5d54040ae358ee0052823503..69bc993dca1929642fcbc1d23cc8066029b2b320 100644
--- a/core/lib/Drupal/Component/FileSystem/FileSystem.php
+++ b/core/lib/Drupal/Component/FileSystem/FileSystem.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Component\FileSystem;
 
+// cspell:ignore winnt
+
 /**
  * Provides file system functions.
  */
diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
index 5f89e0e2bd739bd91b7b113c68cc5699e690c77b..bde03d802d04808cbc3febc46bee9ad4180cf981 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/BackendCompilerPass.php
@@ -24,7 +24,7 @@
  * @endcode
  *
  * As a developer for alternative storage engines you register a service with
- * $yourbackend.$original_service:
+ * $your_backend.$original_service:
  *
  * @code
  * sqlite.custom_service:
diff --git a/core/lib/Drupal/Core/Diff/DiffFormatter.php b/core/lib/Drupal/Core/Diff/DiffFormatter.php
index 52f5550abc9655afd7d6ebfdbdbf30fa47c4f6b6..128428b1bf4999cb7f1dc3c11793cfdd371c598b 100644
--- a/core/lib/Drupal/Core/Diff/DiffFormatter.php
+++ b/core/lib/Drupal/Core/Diff/DiffFormatter.php
@@ -7,6 +7,8 @@
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Config\ConfigFactoryInterface;
 
+// cspell:ignore xbeg, xlen, ybeg, ylen
+
 /**
  * Diff formatter which uses returns output that can be rendered to a table.
  */
diff --git a/core/lib/Drupal/Core/Form/FormBuilder.php b/core/lib/Drupal/Core/Form/FormBuilder.php
index 9fc959cf4c93db9d86d8544fe2cff2e1842bd7b1..8f912ec023b86075dba88c79714cea547853a45d 100644
--- a/core/lib/Drupal/Core/Form/FormBuilder.php
+++ b/core/lib/Drupal/Core/Form/FormBuilder.php
@@ -698,6 +698,7 @@ public function prepareForm($form_id, &$form, FormStateInterface &$form_state) {
       // See https://www.drupal.org/node/2562341.
       // The placeholder uses a unique string that is returned by
       // Crypt::hashBase64('Drupal\Core\Form\FormBuilder::prepareForm').
+      // cspell:disable-next-line
       $placeholder = 'form_action_p_pvdeGsVG5zNF_XLGPTvYSKCf43t8qZYSwcfZl2uzM';
 
       $form['#attached']['placeholders'][$placeholder] = [
diff --git a/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php b/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
index e6728e51206ea7252cc7cdb774f6ebbabde196bb..09a56006a6a3bcd842cf42d882a436ea511c0b88 100644
--- a/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
+++ b/core/lib/Drupal/Core/Mail/Plugin/Mail/PhpMail.php
@@ -8,6 +8,8 @@
 use Symfony\Component\Mime\Header\Headers;
 use Symfony\Component\Mime\Header\UnstructuredHeader;
 
+// cspell:ignore windir
+
 /**
  * Defines the default Drupal mail backend, using PHP's native mail() function.
  *
diff --git a/core/lib/Drupal/Core/ParamConverter/EntityConverter.php b/core/lib/Drupal/Core/ParamConverter/EntityConverter.php
index aa2b00d647647df5528a443f8050486f79c4a3e3..5f7f2efcddbb1ed9abc04600f868ea2beb4b18b5 100644
--- a/core/lib/Drupal/Core/ParamConverter/EntityConverter.php
+++ b/core/lib/Drupal/Core/ParamConverter/EntityConverter.php
@@ -133,7 +133,7 @@ public function convert($value, $definition, $name, array $defaults) {
     }
 
     // Do not inject the context repository as it is not an actual dependency:
-    // it will be removed once both the TODOs below are fixed.
+    // it will be removed once both the todo items below are fixed.
     /** @var \Drupal\Core\Plugin\Context\ContextRepositoryInterface $contexts_repository */
     $contexts_repository = \Drupal::service('context.repository');
     // @todo Consider deprecating the legacy context operation altogether in
diff --git a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
index 9191963f8fcffaa12df18ffda74ee28ca454a1f4..ef4245f45485e574bfc277e2ca4874c895402b2d 100644
--- a/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
+++ b/core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php
@@ -143,8 +143,8 @@ public function getUri();
    *
    * This function should return a URL that can be embedded in a web page
    * and accessed from a browser. For example, the external URL of
-   * "youtube://xIpLd0WQKCY" might be
-   * "http://www.youtube.com/watch?v=xIpLd0WQKCY".
+   * "youtube://random_string" might be
+   * "http://www.youtube.com/watch?v=random_string".
    *
    * @return string
    *   Returns a string containing a web accessible URL for the resource.
diff --git a/core/misc/cspell/dictionary.txt b/core/misc/cspell/dictionary.txt
index 30e1282967d420cf06713f56d97db731863447d8..ec6dd524716fa00f2ad234ef38038fcb55894669 100644
--- a/core/misc/cspell/dictionary.txt
+++ b/core/misc/cspell/dictionary.txt
@@ -899,7 +899,6 @@ pseudotag
 ptablenode
 pterm
 puzzlepiece
-pvde
 pwprompt
 queryor
 querystring
@@ -1111,7 +1110,6 @@ supercede
 svenska
 svgz
 svibanj
-swcf
 sxto
 synchronizable
 syrop
@@ -1138,7 +1136,6 @@ taskless
 tatou
 tbodies
 tcomment
-teletubbies
 tempfile
 templating
 tempstore
@@ -1156,7 +1153,6 @@ testcontent
 testcontextawareblock
 testdescription
 testdialog
-testdisplay
 testen
 testfield
 testfilename
@@ -1179,10 +1175,6 @@ teststring
 testsuite
 testsuites
 testvalue
-testwithleadingslash
-testwithnewline
-testwithslashes
-testwithtrailingslash
 textareas
 textboxes
 texte
@@ -1243,10 +1235,8 @@ typehint
 typehinted
 typehinting
 typehints
-typemanager
 tzid
 uberawesome
-uicrud
 uids
 ulwa
 umami
@@ -1359,32 +1349,25 @@ webp
 webroot
 webservers
 webtest
-webuser
 whitespaces
 whos
 widthx
 wimoids
-windir
 wmet
 wmlscript
 wordprocessingml
 wordsafe
 wordword
 workspaceswitcher
-wqkcy
 writability
 writeln
 wrongparam
 wsod
 wwwrun
-xampl
 xbap
-xbeg
 xbitmap
 xfbml
 xjkm
-xlen
-xlgp
 xmlhttp
 xmlhttprequest
 xoxo
@@ -1396,13 +1379,10 @@ xyabz
 yamls
 yarhar
 yarr
-ybeg
 yearless
-ylen
 yokotsoko
 yottabyte
 yottabytes
-yourbackend
 yourmodule
 yowser
 yqpr
diff --git a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
index ae1038cb21b0f6eede4aee8760211aeca8981968..4d07112856a264e27d184e3d6664e27c1bc70a86 100644
--- a/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentFieldsTest.php
@@ -117,7 +117,7 @@ public function testCommentFieldLinksNonDefaultName() {
       'type' => 'test_node_type',
     ]);
 
-    // Go to the node first so that webuser2 see new comments.
+    // Go to the node first so that web_user2 see new comments.
     $this->drupalLogin($web_user2);
     $this->drupalGet($node->toUrl());
     $this->drupalLogout();
diff --git a/core/modules/editor/src/EditorXssFilterInterface.php b/core/modules/editor/src/EditorXssFilterInterface.php
index 06301bd265c6f20091ee4ef557fc14ebfc3ca7e6..45e03ab6c54bb967fb439eb2c8c70e00241a1f62 100644
--- a/core/modules/editor/src/EditorXssFilterInterface.php
+++ b/core/modules/editor/src/EditorXssFilterInterface.php
@@ -35,7 +35,7 @@ interface EditorXssFilterInterface {
    *   want to adjust the filtering.
    *
    * @return string
-   *   The filtered HTML that cannot cause any XSSes anymore.
+   *   The filtered HTML that cannot cause any XSS anymore.
    */
   public static function filterXss($html, FilterFormatInterface $format, FilterFormatInterface $original_format = NULL);
 
diff --git a/core/modules/pgsql/src/Driver/Database/pgsql/Install/Tasks.php b/core/modules/pgsql/src/Driver/Database/pgsql/Install/Tasks.php
index 078b0342e6fca27cbabc2619620e96cbf310656c..7691422165ef7d43c8535f1cf6e495d894a611e3 100644
--- a/core/modules/pgsql/src/Driver/Database/pgsql/Install/Tasks.php
+++ b/core/modules/pgsql/src/Driver/Database/pgsql/Install/Tasks.php
@@ -6,6 +6,8 @@
 use Drupal\Core\Database\Install\Tasks as InstallTasks;
 use Drupal\Core\Database\DatabaseNotFoundException;
 
+// cspell:ignore trgm
+
 /**
  * Specifies installation tasks for PostgreSQL databases.
  */
diff --git a/core/modules/views/src/Plugin/views/field/EntityField.php b/core/modules/views/src/Plugin/views/field/EntityField.php
index 3f0a63080369bcf3bfec54a3db905d3ddc0c1b24..e6bbda450474881e74e23982ae2be1cdb05c890c 100644
--- a/core/modules/views/src/Plugin/views/field/EntityField.php
+++ b/core/modules/views/src/Plugin/views/field/EntityField.php
@@ -78,7 +78,7 @@ class EntityField extends FieldPluginBase implements CacheableDependencyInterfac
   protected $formatterOptions;
 
   /**
-   * The entity typemanager.
+   * The entity type manager.
    *
    * @var \Drupal\Core\Entity\EntityTypeManagerInterface
    */
diff --git a/core/modules/views_ui/tests/src/Functional/HandlerTest.php b/core/modules/views_ui/tests/src/Functional/HandlerTest.php
index 3f6fef8d92dc9a37a2e76bc48deae63dfe00672e..e8bffb9ab3869de21fb0de0977cc8515b00839ce 100644
--- a/core/modules/views_ui/tests/src/Functional/HandlerTest.php
+++ b/core/modules/views_ui/tests/src/Functional/HandlerTest.php
@@ -94,7 +94,7 @@ protected function viewsData() {
   /**
    * Tests UI CRUD.
    */
-  public function testUICRUD() {
+  public function testUiCrud() {
     $handler_types = ViewExecutable::getHandlerTypes();
     foreach ($handler_types as $type => $type_info) {
       // Test adding handlers.
diff --git a/core/tests/Drupal/KernelTests/Core/TypedData/TypedDataTest.php b/core/tests/Drupal/KernelTests/Core/TypedData/TypedDataTest.php
index 147f39a1d581e458b177832509644c2eaafc8bbb..5687044ec1a1610968def098763568c292471ea1 100644
--- a/core/tests/Drupal/KernelTests/Core/TypedData/TypedDataTest.php
+++ b/core/tests/Drupal/KernelTests/Core/TypedData/TypedDataTest.php
@@ -334,7 +334,7 @@ public function testGetAndSet() {
     $typed_data->setValue(NULL);
     $this->assertNull($typed_data->getValue(), 'Email wrapper is null-able.');
     $this->assertEquals(0, $typed_data->validate()->count());
-    $typed_data->setValue('invalidATexample.com');
+    $typed_data->setValue('invalidAtExample.com');
     $this->assertEquals(1, $typed_data->validate()->count(), 'Validation detected invalid value.');
 
     // Binary type.
diff --git a/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php b/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
index 41e10a9ce171c1d2619f88482b0283c2f8d0f68c..254058339fbd95757778bf02906d2160d9b0c7fe 100644
--- a/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
@@ -54,6 +54,7 @@ public function providerTestValidAbsoluteData() {
       'example.com',
       'www.example.com',
       'ex-ample.com',
+      // cspell:disable-next-line
       '3xampl3.com',
       'example.com/parenthesis',
       'example.com/index.html#pagetop',
diff --git a/core/tests/Drupal/Tests/Component/Utility/UserAgentTest.php b/core/tests/Drupal/Tests/Component/Utility/UserAgentTest.php
index 67f5fee6aa84f4dcd5e1ff9111a65a1a94dee3d5..bb3e69d105aa4273fb21fa51134432b5007d2340 100644
--- a/core/tests/Drupal/Tests/Component/Utility/UserAgentTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/UserAgentTest.php
@@ -6,6 +6,8 @@
 use Drupal\Component\Utility\UserAgent;
 use PHPUnit\Framework\TestCase;
 
+// cspell:ignore Teletubbies
+
 /**
  * Tests bytes size parsing helper methods.
  *
diff --git a/core/tests/Drupal/Tests/Core/Field/FieldFilteredMarkupTest.php b/core/tests/Drupal/Tests/Core/Field/FieldFilteredMarkupTest.php
index ffe6e4470376871a0b78c4a630ae0b8980b97d55..7fcd08f92ee5c0a7756808b36cb31340c262fbb9 100644
--- a/core/tests/Drupal/Tests/Core/Field/FieldFilteredMarkupTest.php
+++ b/core/tests/Drupal/Tests/Core/Field/FieldFilteredMarkupTest.php
@@ -50,7 +50,7 @@ public static function providerTestCreate() {
   /**
    * @covers ::displayAllowedTags
    */
-  public function testdisplayAllowedTags() {
+  public function testDisplayAllowedTags() {
     $expected = '<a> <b> <big> <code> <del> <em> <i> <ins> <pre> <q> <small> <span> <strong> <sub> <sup> <tt> <ol> <ul> <li> <p> <br> <img>';
 
     $this->assertSame($expected, FieldFilteredMarkup::displayAllowedTags());
diff --git a/core/tests/Drupal/Tests/Core/Render/Element/TextfieldTest.php b/core/tests/Drupal/Tests/Core/Render/Element/TextfieldTest.php
index 399eae67d204aef07681260878fa1207a157feef..e15c8578687262ab3b71d6d7a929223cfb2a1f40 100644
--- a/core/tests/Drupal/Tests/Core/Render/Element/TextfieldTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/Element/TextfieldTest.php
@@ -33,7 +33,7 @@ public function providerTestValueCallback() {
     $data[] = ['', ['test']];
     $data[] = ['test', 'test'];
     $data[] = ['123', 123];
-    $data[] = ['testwithnewline', "test\nwith\rnewline"];
+    $data[] = ['testWithNewline', "test\nWith\rNewline"];
 
     return $data;
   }
diff --git a/core/tests/Drupal/Tests/Core/Routing/RouteCompilerTest.php b/core/tests/Drupal/Tests/Core/Routing/RouteCompilerTest.php
index 2d283ebaa2a98ae06daae72a1413ec7e448937a8..2e73bdaeb8bb57a891d443f1fc64815b02c1ca43 100644
--- a/core/tests/Drupal/Tests/Core/Routing/RouteCompilerTest.php
+++ b/core/tests/Drupal/Tests/Core/Routing/RouteCompilerTest.php
@@ -40,9 +40,9 @@ public function testGetFit($path, $expected) {
   public function providerTestGetFit() {
     return [
       ['test', 1],
-      ['/testwithleadingslash', 1],
-      ['testwithtrailingslash/', 1],
-      ['/testwithslashes/', 1],
+      ['/estWithLeadingSlash', 1],
+      ['testWithTrailingslash/', 1],
+      ['/testWithSlashes/', 1],
       ['test/with/multiple/parts', 15],
       ['test/with/{some}/slugs', 13],
       ['test/very/long/path/that/drupal/7/could/not/have/handled', 2047],