diff --git a/core/includes/form.inc b/core/includes/form.inc
index 87f8edfc66b0ae1d99dfdedecd382978053de27e..e4f7982fb85e4853be20af16be962937817cc30e 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -1674,7 +1674,7 @@ function form_process_table($element, &$form_state) {
     if ($element['#multiple']) {
       $value = is_array($element['#value']) ? $element['#value'] : array();
     }
-    // Advanced selection behaviour makes no sense for radios.
+    // Advanced selection behavior makes no sense for radios.
     else {
       $element['#js_select'] = FALSE;
     }
diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
index 7be16b3db806269e901abcd7a8d752468dc91af5..620b82911ee7fb875514d83fb2bd792836fef1df 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
@@ -74,7 +74,7 @@ public static function open(array &$connection_options = array()) {
       \PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => TRUE,
       // Make sure MySQL returns all matched rows on update queries including
       // rows that actually didn't have to be updated because the values didn't
-      // change. This matches common behaviour among other database systems.
+      // change. This matches common behavior among other database systems.
       \PDO::MYSQL_ATTR_FOUND_ROWS => TRUE,
       // Because MySQL's prepared statements skip the query cache, because it's dumb.
       \PDO::ATTR_EMULATE_PREPARES => TRUE,
diff --git a/core/misc/ajax.js b/core/misc/ajax.js
index 3754af6c771e6c30915083f6c9f91e74797369c4..4abb652d8ee5dd4e073a4d5c7c6af7f23a7db52e 100644
--- a/core/misc/ajax.js
+++ b/core/misc/ajax.js
@@ -22,7 +22,7 @@ Drupal.ajax = Drupal.ajax || {};
 Drupal.behaviors.AJAX = {
   attach: function (context, settings) {
 
-    function loadAjaxBehaviour(base) {
+    function loadAjaxBehavior(base) {
       var element_settings = settings.ajax[base];
       if (typeof element_settings.selector === 'undefined') {
         element_settings.selector = '#' + base;
@@ -36,7 +36,7 @@ Drupal.behaviors.AJAX = {
     // Load all Ajax behaviors specified in the settings.
     for (var base in settings.ajax) {
       if (settings.ajax.hasOwnProperty(base)) {
-        loadAjaxBehaviour(base);
+        loadAjaxBehavior(base);
       }
     }
 
diff --git a/core/misc/tabledrag.js b/core/misc/tabledrag.js
index e78d6935f4bd684f1876c305d9212ca1127a565e..68be8f6382e4fb42ad53c57d33044ac939eecc2d 100644
--- a/core/misc/tabledrag.js
+++ b/core/misc/tabledrag.js
@@ -578,7 +578,7 @@ Drupal.tableDrag.prototype.dragRow = function (event, self) {
 };
 
 /**
- * Pointerup behaviour.
+ * Pointerup behavior.
  */
 Drupal.tableDrag.prototype.dropRow = function (event, self) {
   var droppedRow, $droppedRow;
diff --git a/core/modules/comment/lib/Drupal/comment/CommentManagerInterface.php b/core/modules/comment/lib/Drupal/comment/CommentManagerInterface.php
index b1747f2ab8c827a65d02d20f86bb789a0b1e3c02..b1805e53369b3a9eed2b7a0b9a598e6fee9d60bd 100644
--- a/core/modules/comment/lib/Drupal/comment/CommentManagerInterface.php
+++ b/core/modules/comment/lib/Drupal/comment/CommentManagerInterface.php
@@ -49,7 +49,7 @@ public function getAllFields();
    * Utility method to add the default comment field to an entity.
    *
    * Attaches a comment field named 'comment' to the given entity type and
-   * bundle. Largely replicates the default behaviour in Drupal 7 and earlier.
+   * bundle. Largely replicates the default behavior in Drupal 7 and earlier.
    *
    * @param string $entity_type
    *   The entity type to attach the default comment field to.
diff --git a/core/modules/locale/lib/Drupal/locale/Form/LocaleSettingsForm.php b/core/modules/locale/lib/Drupal/locale/Form/LocaleSettingsForm.php
index 2cd2bad5ae18d8455fe3568dc092282d7d72fa2f..6ed319563813db5d0b7d8fde4bd40688dc596e45 100644
--- a/core/modules/locale/lib/Drupal/locale/Form/LocaleSettingsForm.php
+++ b/core/modules/locale/lib/Drupal/locale/Form/LocaleSettingsForm.php
@@ -67,7 +67,7 @@ public function buildForm(array $form, array &$form_state) {
     }
     $form['overwrite'] = array(
       '#type' => 'radios',
-      '#title' => t('Import behaviour'),
+      '#title' => t('Import behavior'),
       '#default_value' => $default,
       '#options' => array(
         LOCALE_TRANSLATION_OVERWRITE_NONE => t("Don't overwrite existing translations."),
diff --git a/core/modules/menu_link/menu_link.module b/core/modules/menu_link/menu_link.module
index 5a393de3788dc3b4bc40bfd9e000e54bd914d7bb..6757a4edb53794da0fcac811468c6f1e35c4ca57 100644
--- a/core/modules/menu_link/menu_link.module
+++ b/core/modules/menu_link/menu_link.module
@@ -202,7 +202,7 @@ function menu_link_maintain($module, $op, $link_path, $link_title = NULL) {
  * Implements hook_system_breadcrumb_alter().
  */
 function menu_link_system_breadcrumb_alter(array &$breadcrumb, array $attributes, array $context) {
-  // Custom breadcrumb behaviour for editing menu links, we append a link to
+  // Custom breadcrumb behavior for editing menu links, we append a link to
   // the menu in which the link is found.
   if (!empty($attributes[RouteObjectInterface::ROUTE_NAME]) && $attributes[RouteObjectInterface::ROUTE_NAME] == 'menu.link_edit' && !empty($attributes['menu_link'])) {
     $menu_link = $attributes['menu_link'];
diff --git a/core/modules/system/entity.api.php b/core/modules/system/entity.api.php
index 4256f83072946324882a44dcf74a8c06a8cb2396..451de06e980c19752188f13c5d308e92547bd8ab 100644
--- a/core/modules/system/entity.api.php
+++ b/core/modules/system/entity.api.php
@@ -736,7 +736,7 @@ function hook_entity_field_access($operation, \Drupal\Core\Field\FieldDefinition
 }
 
 /**
- * Alters the default access behaviour for a given field.
+ * Alters the default access behavior for a given field.
  *
  * Use this hook to override access grants from another module. Note that the
  * original default access flag is masked under the ':default' key.
diff --git a/core/modules/system/lib/Drupal/system/Tests/Database/UpdateTest.php b/core/modules/system/lib/Drupal/system/Tests/Database/UpdateTest.php
index ba64792439eaf83bb44a2d02335050c06a75e965..8038f63a4a04e92f7e55c25ca4e5331667d5403c 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Database/UpdateTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Database/UpdateTest.php
@@ -130,7 +130,7 @@ function testUpdateAffectedRows() {
     // condition and therefore are affected by the query, even though two of
     // them actually don't have to be changed because their value was already
     // 'sleep'. Still, execute() should return 5 affected rows, not only 3,
-    // because that's cross-db expected behaviour.
+    // because that's cross-db expected behavior.
     $num_rows = db_update('test_task')
       ->condition('priority', 1, '<>')
       ->fields(array('task' => 'sleep'))
diff --git a/core/modules/system/tests/modules/form_test/form_test.module b/core/modules/system/tests/modules/form_test/form_test.module
index ecdbc7634f014dd6a4a525a6f81d6cf64dcbba51..922bc784453f95d21c10d9be5bee4f894833af52 100644
--- a/core/modules/system/tests/modules/form_test/form_test.module
+++ b/core/modules/system/tests/modules/form_test/form_test.module
@@ -1952,7 +1952,7 @@ function form_test_redirect($form, &$form_state) {
 }
 
 /**
- * Form submit handler to test different redirect behaviours.
+ * Form submit handler to test different redirect behaviors.
  */
 function form_test_redirect_submit(&$form, &$form_state) {
   if (!empty($form_state['values']['redirection'])) {
diff --git a/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayPageTest.php b/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayPageTest.php
index b81fe7dbcde61b039c8ad42b025af4133586ca69..03862ade1eb2067d0e2fe8408304bd7281c663a8 100644
--- a/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayPageTest.php
+++ b/core/modules/views/lib/Drupal/views/Tests/Plugin/DisplayPageTest.php
@@ -62,7 +62,7 @@ protected function setUp() {
   }
 
   /**
-   * Checks the behavior of the page for access denied/not found behaviours.
+   * Checks the behavior of the page for access denied/not found behaviors.
    */
   public function testPageResponses() {
     // @todo Importing a route should fire a container rebuild.
diff --git a/core/modules/views/lib/Drupal/views/Tests/Plugin/PagerTest.php b/core/modules/views/lib/Drupal/views/Tests/Plugin/PagerTest.php
index 20d300cf4e1ed04325deee52f346f3e38ed0d09c..7cb233e8932bf9e53aee9a4cbdbd78b12bd07409 100644
--- a/core/modules/views/lib/Drupal/views/Tests/Plugin/PagerTest.php
+++ b/core/modules/views/lib/Drupal/views/Tests/Plugin/PagerTest.php
@@ -42,7 +42,7 @@ public static function getInfo() {
   public function testStorePagerSettings() {
     $admin_user = $this->drupalCreateUser(array('administer views', 'administer site configuration'));
     $this->drupalLogin($admin_user);
-    // Test behaviour described in http://drupal.org/node/652712#comment-2354918.
+    // Test behavior described in http://drupal.org/node/652712#comment-2354918.
 
     $this->drupalGet('admin/structure/views/view/test_view/edit');
 
@@ -64,7 +64,7 @@ public function testStorePagerSettings() {
     $this->drupalGet('admin/structure/views/view/test_view/edit');
     $this->assertText('Mini', 'Changed pager plugin, should change some text');
 
-    // Test behaviour described in http://drupal.org/node/652712#comment-2354400
+    // Test behavior described in http://drupal.org/node/652712#comment-2354400
     $view = views_get_view('test_store_pager_settings');
     // Make it editable in the admin interface.
     $view->save();
diff --git a/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
index 1850903831d781a2874f4db7c7be5a31d9d3dd0a..a0a1b4d44948391233684a2706eb0c104b2461d7 100644
--- a/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
+++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
@@ -354,7 +354,7 @@ public function testNonExistingTableGetCache() {
   }
 
   /**
-   * Tests the cache backend behaviour with requesting the same table multiple
+   * Tests the cache backend behavior with requesting the same table multiple
    */
   public function testCacheCallsWithSameTableMultipleTimes() {
     $expected_views_data = $this->viewsData();
diff --git a/core/modules/views/views.api.php b/core/modules/views/views.api.php
index 4ba2a3c01b553221efdeb6df73b27d7541721403..d48f78957bc6e6f47f1d3c6388d75952a9840dd8 100644
--- a/core/modules/views/views.api.php
+++ b/core/modules/views/views.api.php
@@ -185,7 +185,7 @@ function hook_views_data() {
   //   - filter: A description of any filter handler for the table field.
   //   - argument: A description of any argument handler for the table field.
   //   - area: A description of any handler for adding content to header,
-  //     footer or as no result behaviour.
+  //     footer or as no result behavior.
   //
   // The handler descriptions are described with examples below.