diff --git a/core/lib/Drupal/Component/Utility/Unicode.php b/core/lib/Drupal/Component/Utility/Unicode.php
index 4a63ec2e47..657d9ff795 100644
--- a/core/lib/Drupal/Component/Utility/Unicode.php
+++ b/core/lib/Drupal/Component/Utility/Unicode.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Component\Utility;
 
+// cspell:ignore myverylongurl myverylongurlexample
+
 /**
  * Provides Unicode-related conversions and operations.
  *
diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
index 0f2bdb038a..c0e71ec2f8 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/TwigExtensionPass.php
@@ -9,8 +9,8 @@
 /**
  * Adds the twig_extension_hash parameter to the container.
  *
- * Parameter twig_extension_hash is a hash of all extension mtimes for Twig
- * template invalidation.
+ * Parameter twig_extension_hash is a hash of all extension modification times
+ * or Twig template invalidation.
  */
 class TwigExtensionPass implements CompilerPassInterface {
 
diff --git a/core/lib/Drupal/Core/Utility/ThemeRegistry.php b/core/lib/Drupal/Core/Utility/ThemeRegistry.php
index 8abb17d780..9b3970f2a0 100644
--- a/core/lib/Drupal/Core/Utility/ThemeRegistry.php
+++ b/core/lib/Drupal/Core/Utility/ThemeRegistry.php
@@ -55,7 +55,7 @@ public function __construct($cid, CacheBackendInterface $cache, LockBackendInter
     $this->tags = $tags;
     $this->persistable = $modules_loaded && \Drupal::hasRequest() && \Drupal::request()->isMethod('GET');
 
-    // @todo: Implement lazyload.
+    // @todo: Implement lazy-loading.
     $this->cacheLoaded = TRUE;
 
     if ($this->persistable && $cached = $this->cache->get($this->cid)) {
diff --git a/core/misc/cspell/dictionary.txt b/core/misc/cspell/dictionary.txt
index 00b29f95c6..84a476cda9 100644
--- a/core/misc/cspell/dictionary.txt
+++ b/core/misc/cspell/dictionary.txt
@@ -666,7 +666,6 @@ kontex
 kpresenter
 kristiaan
 kspread
-kthxbai
 kword
 laatste
 labely
@@ -675,9 +674,7 @@ langcode
 langcodes
 langname
 languageswitcher
-layouted
 lazybuilder
-lazyload
 lcode
 leftjoin
 libc
@@ -698,7 +695,6 @@ linkification
 linksby
 linktext
 lisu
-litererally
 llamaids
 llamasarelame
 llamma
@@ -716,8 +712,6 @@ loquesea
 loreming
 loremingipsum
 loremipsum
-loremipsumloremipsum
-lowlevel
 lowline
 lrdd
 lstitle
@@ -735,7 +729,6 @@ makealternatemessage
 makedefaultmessage
 makewarningmessage
 makz
-mame
 mank
 maryjane
 marz
@@ -758,13 +751,11 @@ mediumtext
 membersonly
 merhaba
 messagekey
-metainformation
 metapackage
 metapackages
 metatag
 metatags
 meφω
-miaus
 middlewares
 midgardmvc
 mikey
@@ -774,14 +765,11 @@ minifyzombies
 minimatch
 minimise
 minipager
-minky
 minusthick
 missingkey
 missingkeys
-mjuc
 mlfr
 mlid
-mlids
 moby
 mocktail
 mocktails
@@ -795,16 +783,13 @@ montag
 monthnames
 moono
 mooooh
-mosie
 mostrar
 moutons
 moyenne
-mple
 msgctxt
 msgid
 msgstr
 msword
-mtimes
 mucho
 mulrev
 mulrevpub
@@ -831,8 +816,6 @@ mymodule
 mysite
 mysqladmin
 mysqldump
-mystarterkit
-myverylongurl
 myverylongurlexample
 műveletek
 nalias
diff --git a/core/modules/book/src/BookManagerInterface.php b/core/modules/book/src/BookManagerInterface.php
index 44107f2f90..1a1723c583 100644
--- a/core/modules/book/src/BookManagerInterface.php
+++ b/core/modules/book/src/BookManagerInterface.php
@@ -44,7 +44,7 @@ public function bookTreeAllData($bid, $link = NULL, $max_depth = NULL);
    *   A fully loaded menu link.
    *
    * @return array
-   *   An array containing the active trail: a list of mlids.
+   *   An array containing the active trail: a list of menu link IDs.
    */
   public function getActiveTrailIds($bid, $link);
 
diff --git a/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php b/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
index 098c50e404..9867153f02 100644
--- a/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
+++ b/core/modules/comment/tests/src/Functional/CommentInterfaceTest.php
@@ -247,9 +247,10 @@ public function testAutoFilledSubject() {
     $this->assertEquals('Lorem ipsum Lorem ipsum…', $comment1->getSubject());
 
     // Break at 29 characters where there's no boundary before that.
-    $body_text2 = 'LoremipsumloremipsumLoremingipsumLoremipsum';
+    // Ignores spell checking for Lorempsum.
+    $body_text2 = 'LoremIpsumLoremIpsumLoremingIpsumLorempsum';
     $comment2 = $this->postComment(NULL, $body_text2, '', TRUE);
-    $this->assertEquals('LoremipsumloremipsumLoreming…', $comment2->getSubject());
+    $this->assertEquals('LoremIpsumLoremIpsumLoreming…', $comment2->getSubject());
   }
 
   /**
diff --git a/core/modules/comment/tests/src/Kernel/CommentFieldAccessTest.php b/core/modules/comment/tests/src/Kernel/CommentFieldAccessTest.php
index 0d96303232..c7dea4d622 100644
--- a/core/modules/comment/tests/src/Kernel/CommentFieldAccessTest.php
+++ b/core/modules/comment/tests/src/Kernel/CommentFieldAccessTest.php
@@ -178,7 +178,7 @@ public function testAccessToAdministrativeFields() {
       'hostname' => 'magic.example.com',
       // Unpublished.
       'status' => 0,
-      'subject' => 'Gail the minky whale',
+      'subject' => 'Gail the minke whale',
       'entity_id' => $host->id(),
       'comment_type' => 'comment',
       'field_name' => 'comment_other',
diff --git a/core/modules/filter/tests/src/Kernel/FilterKernelTest.php b/core/modules/filter/tests/src/Kernel/FilterKernelTest.php
index c7f9b5fadf..924c81abb5 100644
--- a/core/modules/filter/tests/src/Kernel/FilterKernelTest.php
+++ b/core/modules/filter/tests/src/Kernel/FilterKernelTest.php
@@ -761,7 +761,7 @@ public function testUrlFilter() {
       '
 <p>Test &lt;br/&gt;: This is a www.example17.com example <strong>with</strong> various http://www.example18.com tags. *<br/>
  It is important www.example19.com to *<br/>test different URLs and http://www.example20.com in the same paragraph. *<br>
-HTML www.example21.com soup by person@example22.com can litererally http://www.example23.com contain *img*<img> anything. Just a www.example24.com with http://www.example25.com thrown in. www.example26.com from person@example27.com with extra http://www.example28.com.
+  HTML www.example21.com soup by person@example22.com can literally http://www.example23.com contain *img*<img> anything. Just a www.example24.com with http://www.example25.com thrown in. www.example26.com from person@example27.com with extra http://www.example28.com.
 ' => [
         'href="http://www.example17.com"' => TRUE,
         'href="http://www.example18.com"' => TRUE,
diff --git a/core/modules/image/tests/src/Kernel/ImageItemTest.php b/core/modules/image/tests/src/Kernel/ImageItemTest.php
index 2884747213..cbb75f1c5b 100644
--- a/core/modules/image/tests/src/Kernel/ImageItemTest.php
+++ b/core/modules/image/tests/src/Kernel/ImageItemTest.php
@@ -125,7 +125,7 @@ public function testImageItem() {
 
     // Delete the image and try to save the entity again.
     $this->image->delete();
-    $entity = EntityTest::create(['mame' => $this->randomMachineName()]);
+    $entity = EntityTest::create(['name' => $this->randomMachineName()]);
     $entity->save();
 
     // Test image item properties.
diff --git a/core/modules/jsonapi/tests/src/Functional/JsonApiRegressionTest.php b/core/modules/jsonapi/tests/src/Functional/JsonApiRegressionTest.php
index f17fba164b..0eae56573b 100644
--- a/core/modules/jsonapi/tests/src/Functional/JsonApiRegressionTest.php
+++ b/core/modules/jsonapi/tests/src/Functional/JsonApiRegressionTest.php
@@ -500,7 +500,7 @@ public function testThatRoutesAreRebuiltAfterDataModelChangesFromIssue2984886()
     $this->createEntityReferenceField('node', 'dog', 'field_test', NULL, 'node');
     \Drupal::service('router.builder')->rebuildIfNeeded();
 
-    $dog = Node::create(['type' => 'dog', 'title' => 'Rosie P. Mosie']);
+    $dog = Node::create(['type' => 'dog', 'title' => 'retriever']);
     $dog->save();
 
     $response = $this->request('GET', Url::fromUri('internal:/jsonapi/node/dog/' . $dog->uuid() . '/field_test'), $request_options);
diff --git a/core/modules/layout_builder/tests/src/FunctionalJavascript/ItemLayoutFieldBlockTest.php b/core/modules/layout_builder/tests/src/FunctionalJavascript/ItemLayoutFieldBlockTest.php
index eba608cdc1..f8506215d1 100644
--- a/core/modules/layout_builder/tests/src/FunctionalJavascript/ItemLayoutFieldBlockTest.php
+++ b/core/modules/layout_builder/tests/src/FunctionalJavascript/ItemLayoutFieldBlockTest.php
@@ -69,7 +69,7 @@ public function testAddAjaxBlock() {
     $this->clickLink('Add block');
     $assert_session->assertWaitOnAjaxRequest();
 
-    // Validate that only field blocks for layouted bundle are present.
+    // Validate that only field blocks for the layout bundle are present.
     $valid_links = $page->findAll('css', 'a[href$="field_block%3Anode%3Abundle_with_layout_overrides%3Abody"]');
     $this->assertCount(1, $valid_links);
     $invalid_links = $page->findAll('css', 'a[href$="field_block%3Anode%3Afiller_bundle%3Abody"]');
diff --git a/core/modules/menu_ui/src/MenuForm.php b/core/modules/menu_ui/src/MenuForm.php
index 599eb93c74..13551e06b9 100644
--- a/core/modules/menu_ui/src/MenuForm.php
+++ b/core/modules/menu_ui/src/MenuForm.php
@@ -527,7 +527,7 @@ protected function submitOverviewForm(array $complete_form, FormStateInterface $
         if ($updated_values) {
           // Use the ID from the actual plugin instance since the hidden value
           // in the form could be tampered with.
-          $this->menuLinkManager->updateDefinition($element['#item']->link->getPLuginId(), $updated_values);
+          $this->menuLinkManager->updateDefinition($element['#item']->link->getPluginId(), $updated_values);
         }
       }
     }
diff --git a/core/modules/quickedit/tests/src/Functional/QuickEditEndPointAccessTest.php b/core/modules/quickedit/tests/src/Functional/QuickEditEndPointAccessTest.php
index cd367e0a09..c0c8dc0188 100644
--- a/core/modules/quickedit/tests/src/Functional/QuickEditEndPointAccessTest.php
+++ b/core/modules/quickedit/tests/src/Functional/QuickEditEndPointAccessTest.php
@@ -57,6 +57,7 @@ public function testEndPointAccess() {
 
     $edit = [];
     $edit['form_id'] = 'quickedit_field_form';
+    // cspell:disable-next-line
     $edit['form_token'] = 'xIOzMjuc-PULKsRn_KxFn7xzNk5Bx7XKXLfQfw1qOnA';
     $edit['form_build_id'] = 'form-kVmovBpyX-SJfTT5kY0pjTV35TV-znor--a64dEnMR8';
     $edit['body[0][summary]'] = '';
diff --git a/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php b/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
index f20a753b71..d6983596dd 100644
--- a/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
+++ b/core/modules/system/tests/src/Functional/Form/ElementsTableSelectTest.php
@@ -241,7 +241,7 @@ private function formSubmitHelper($form, $edit) {
     $form_state->clearErrors();
 
     // Return the processed form together with form_state and errors
-    // to allow the caller lowlevel access to the form.
+    // to allow the caller low-level access to the form.
     return [$form, $form_state, $errors];
   }
 
diff --git a/core/modules/views/tests/src/Functional/Handler/HandlerAllTest.php b/core/modules/views/tests/src/Functional/Handler/HandlerAllTest.php
index 52925792a8..4477e93515 100644
--- a/core/modules/views/tests/src/Functional/Handler/HandlerAllTest.php
+++ b/core/modules/views/tests/src/Functional/Handler/HandlerAllTest.php
@@ -70,7 +70,7 @@ public function testHandlers() {
 
       // Go through all fields and there through all handler types.
       foreach ($info as $field => $field_info) {
-        // Table is a reserved key for the metainformation.
+        // Table is a reserved key for the meta-information.
         if ($field != 'table' && !in_array("$base_table:$field", $exclude)) {
           $item = [
             'table' => $base_table,
diff --git a/core/tests/Drupal/KernelTests/Config/TypedConfigTest.php b/core/tests/Drupal/KernelTests/Config/TypedConfigTest.php
index 7a40310b31..c050f32df3 100644
--- a/core/tests/Drupal/KernelTests/Config/TypedConfigTest.php
+++ b/core/tests/Drupal/KernelTests/Config/TypedConfigTest.php
@@ -123,7 +123,7 @@ public function testSimpleConfigValidation() {
     $this->assertEmpty($result);
 
     // Test constrains on nested mapping.
-    $config->set('cat.type', 'miaus');
+    $config->set('cat.type', 'tiger');
     $config->save();
 
     $typed_config = $typed_config_manager->get('config_test.validation');
diff --git a/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php b/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
index 5a67b0483a..e9a275e9f9 100644
--- a/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/UrlHelperTest.php
@@ -164,6 +164,7 @@ public function testValidRelative($url, $prefix) {
    */
   public function providerTestInvalidRelativeData() {
     $data = [
+      // cspell:disable-next-line
       'ex^mple',
       'example<>',
       'ex%ample',
diff --git a/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
index f9006bb3db..ef5fd07a24 100644
--- a/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererPlaceholdersTest.php
@@ -930,7 +930,7 @@ public function testChildrenPlusBuilder() {
     $element = [];
     $element['#lazy_builder'] = ['Drupal\Tests\Core\Render\RecursivePlaceholdersTest::callback', []];
     $element['child_a']['#markup'] = 'Oh hai!';
-    $element['child_b']['#markup'] = 'kthxbai';
+    $element['child_b']['#markup'] = 'goodbye';
 
     $this->expectException(\AssertionError::class);
     $this->expectExceptionMessage('When a #lazy_builder callback is specified, no children can exist; all children must be generated by the #lazy_builder callback. You specified the following children: child_a, child_b.');