diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index bbb8882..0c5a096 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -323,18 +323,18 @@ function comment_node_type_delete($info) {
 function _comment_body_field_create($info) {
   // Create the field if needed.
   if (!field_read_field('comment_body', array('include_inactive' => TRUE))) {
-    $field = entity_create('field_config', array(
+    $field_config = entity_create('field_config', array(
       'field_name' => 'comment_body',
       'type' => 'text_long',
       'entity_types' => array('comment'),
     ));
-    $field->save();
+    $field_config->save();
   }
   // Create the instance if needed.
   if (!field_read_instance('comment', 'comment_body', 'comment_node_' . $info->type, array('include_inactive' => TRUE))) {
     entity_invoke_bundle_hook('create', 'comment', 'comment_node_' . $info->type);
     // Attaches the body field by default.
-    $instance = entity_create('field_instance_config', array(
+    $field_instance_config = entity_create('field_instance_config', array(
       'field_name' => 'comment_body',
       'label' => 'Comment',
       'entity_type' => 'comment',
@@ -342,7 +342,7 @@ function _comment_body_field_create($info) {
       'settings' => array('text_processing' => 1),
       'required' => TRUE,
     ));
-    $instance->save();
+    $field_instance_config->save();
 
     // Assign widget settings for the 'default' form mode.
     entity_get_form_display('comment', 'comment_node_' . $info->type, 'default')
diff --git a/core/modules/datetime/lib/Drupal/datetime/Tests/DateTimeItemTest.php b/core/modules/datetime/lib/Drupal/datetime/Tests/DateTimeItemTest.php
index 16731a2..3c64d93 100644
--- a/core/modules/datetime/lib/Drupal/datetime/Tests/DateTimeItemTest.php
+++ b/core/modules/datetime/lib/Drupal/datetime/Tests/DateTimeItemTest.php
@@ -35,21 +35,21 @@ public function setUp() {
     parent::setUp();
 
     // Create a field with settings to validate.
-    $this->field = entity_create('field_entity', array(
+    $this->field_config = entity_create('field_config', array(
       'field_name' => 'field_datetime',
       'type' => 'datetime',
       'settings' => array('datetime_type' => 'date'),
     ));
-    $this->field->save();
-    $this->instance = entity_create('field_instance', array(
-      'field_name' => $this->field['field_name'],
+    $this->field_config->save();
+    $this->field_instance_config = entity_create('field_instance_config', array(
+      'field_name' => $this->field_config['field_name'],
       'entity_type' => 'entity_test',
       'bundle' => 'entity_test',
       'settings' => array(
         'default_value' => 'blank',
       ),
     ));
-    $this->instance->save();
+    $this->field_instance_config->save();
   }
 
   /**
diff --git a/core/modules/file/file.install b/core/modules/file/file.install
index 6e5ca53..508ede1 100644
--- a/core/modules/file/file.install
+++ b/core/modules/file/file.install
@@ -305,20 +305,20 @@ function file_update_8003() {
     $field_config_raw = config($config_name);
     // Only update file fields that use the default SQL storage.
     if (in_array($field_config_raw->get('type'), array('file', 'image')) && $field_config_raw->get('storage.type') == 'field_sql_storage') {
-      $field = new FieldConfig($field_config_raw->get());
+      $field_config = new FieldConfig($field_config_raw->get());
 
       $tables = array(
-        _field_sql_storage_tablename($field),
-        _field_sql_storage_revision_tablename($field),
+        _field_sql_storage_tablename($field_config),
+        _field_sql_storage_revision_tablename($field_config),
       );
 
       foreach ($tables as $table_name) {
         // Skip fields which were created during the upgrade process.
-        if (!db_field_exists($table_name, $field->id() . '_fid')) {
+        if (!db_field_exists($table_name, $field_config->id() . '_fid')) {
           continue 2;
         }
 
-        db_change_field($table_name, $field->id() . '_fid', $field->id() . '_target_id', array(
+        db_change_field($table_name, $field_config->id() . '_fid', $field_config->id() . '_target_id', array(
           'description' => 'The ID of the target entity.',
           'type' => 'int',
           'unsigned' => TRUE,
@@ -326,8 +326,8 @@ function file_update_8003() {
         ));
 
         // Change the index.
-        db_drop_index($table_name, $field->id() . '_fid');
-        db_add_index($table_name, $field->id() . '_target_id', array($field->id() . '_target_id'));
+        db_drop_index($table_name, $field_config->id() . '_fid');
+        db_add_index($table_name, $field_config->id() . '_target_id', array($field_config->id() . '_target_id'));
       }
 
       // Update the indexes in field config as well.
diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index 91842cf..52206d0 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -730,7 +730,7 @@ function image_field_instance_config_update(FieldInstanceConfigInterface $field_
 /**
  * Implements hook_ENTITY_TYPE_delete() for 'field_config'.
  */
-function image_field_entity_delete(FieldConfigInterface $field_config) {
+function image_field_config_delete(FieldConfigInterface $field_config) {
   if ($field_config->type != 'image') {
     // Only act on image fields.
     return;
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index 29c6540..4e38c16 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -395,49 +395,49 @@ function node_type_load($name) {
  */
 function node_add_body_field(NodeTypeInterface $type, $label = 'Body') {
    // Add or remove the body field, as needed.
-  $field = field_info_field('body');
+  $field_config = field_info_field('body');
   $instance = field_info_instance('node', 'body', $type->id());
-  if (empty($field)) {
-    $field = entity_create('field_config', array(
+  if (empty($field_config)) {
+    $field_config = entity_create('field_config', array(
       'field_name' => 'body',
       'type' => 'text_with_summary',
       'entity_types' => array('node'),
     ));
-    $field->save();
+    $field_config->save();
   }
-  if (empty($instance)) {
-    $instance = entity_create('field_instance_config', array(
+  if (empty($field_instance_config)) {
+    $field_instance_config = entity_create('field_instance_config', array(
       'field_name' => 'body',
       'entity_type' => 'node',
       'bundle' => $type->id(),
       'label' => $label,
       'settings' => array('display_summary' => TRUE),
     ));
-    $instance->save();
+    $field_instance_config->save();
 
     // Assign widget settings for the 'default' form mode.
     entity_get_form_display('node', $type->type, 'default')
-      ->setComponent($field->id(), array(
+      ->setComponent($field_config->id(), array(
         'type' => 'text_textarea_with_summary',
       ))
       ->save();
 
     // Assign display settings for the 'default' and 'teaser' view modes.
     entity_get_display('node', $type->type, 'default')
-      ->setComponent($field->id(), array(
+      ->setComponent($field_config->id(), array(
         'label' => 'hidden',
         'type' => 'text_default',
       ))
       ->save();
     entity_get_display('node', $type->type, 'teaser')
-      ->setComponent($field->id(), array(
+      ->setComponent($field_config->id(), array(
         'label' => 'hidden',
         'type' => 'text_summary_or_trimmed',
       ))
       ->save();
   }
 
-  return $instance;
+  return $field_instance_config;
 }
 
 /**
diff --git a/core/modules/taxonomy/taxonomy.install b/core/modules/taxonomy/taxonomy.install
index 2be0417..2743467 100644
--- a/core/modules/taxonomy/taxonomy.install
+++ b/core/modules/taxonomy/taxonomy.install
@@ -354,18 +354,18 @@ function taxonomy_update_8006() {
  */
 function taxonomy_update_8007() {
   foreach (config_get_storage_names_with_prefix('field.field.') as $config_name) {
-    $field_config = config($config_name);
+    $field_config_raw = config($config_name);
     // Only update taxonomy reference fields that use the default SQL storage.
-    if ($field_config->get('type') == 'taxonomy_term_reference' && $field_config->get('storage.type') == 'field_sql_storage') {
-      $field = new FieldConfig($field_config->get());
+    if ($field_config_raw->get('type') == 'taxonomy_term_reference' && $field_config_raw->get('storage.type') == 'field_sql_storage') {
+      $field_config = new FieldConfig($field_config_raw->get());
 
       $tables = array(
-        _field_sql_storage_tablename($field),
-        _field_sql_storage_revision_tablename($field),
+        _field_sql_storage_tablename($field_config),
+        _field_sql_storage_revision_tablename($field_config),
       );
 
       foreach ($tables as $table_name) {
-        db_change_field($table_name, $field->id() . '_tid', $field->id() . '_target_id', array(
+        db_change_field($table_name, $field_config->id() . '_tid', $field_config->id() . '_target_id', array(
           'description' => 'The ID of the target entity.',
           'type' => 'int',
           'unsigned' => TRUE,
@@ -373,16 +373,16 @@ function taxonomy_update_8007() {
         ));
 
         // Change the index.
-        db_drop_index($table_name, $field->id() . '_tid');
-        db_add_index($table_name, $field->id() . '_target_id', array($field->id() . '_target_id'));
+        db_drop_index($table_name, $field_config->id() . '_tid');
+        db_add_index($table_name, $field_config->id() . '_target_id', array($field_config->id() . '_target_id'));
       }
 
       // Update the indexes in field config as well.
-      $indexes = $field_config->get('indexes');
+      $indexes = $field_config_raw->get('indexes');
       unset($indexes['tid']);
       $indexes['target_id'] = array('target_id');
-      $field_config->set('indexes', $indexes);
-      $field_config->save();
+      $field_config_raw->set('indexes', $indexes);
+      $field_config_raw->save();
     }
   }
 }
diff --git a/core/modules/user/lib/Drupal/user/Tests/UserCreateTest.php b/core/modules/user/lib/Drupal/user/Tests/UserCreateTest.php
index 2026e5c..f0d5454 100644
--- a/core/modules/user/lib/Drupal/user/Tests/UserCreateTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserCreateTest.php
@@ -39,7 +39,7 @@ protected function testUserAdd() {
 
     // Create a field and an instance.
     $field_name = 'test_field';
-    $field = array(
+    $field_config = array(
       'field_name' => $field_name,
       'module' => 'image',
       'type' => 'image',
@@ -51,9 +51,9 @@ protected function testUserAdd() {
         'default_image' => FALSE,
       ),
     );
-    entity_create('field_entity', $field)->save();
+    entity_create('field_config', $field_config)->save();
 
-    $instance = array(
+    $field_instance_config = array(
       'field_name' => $field_name,
       'entity_type' => 'user',
       'label' => 'Picture',
@@ -71,7 +71,7 @@ protected function testUserAdd() {
         'default_image' => 0,
       ),
     );
-    entity_create('field_instance', $instance)->save();
+    entity_create('field_instance_config', $field_instance_config)->save();
 
     // Test user creation page for valid fields.
     $this->drupalGet('admin/people/create');