diff --git a/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
index 13f853d..8c92237 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/AnnotatedClassDiscovery.php
@@ -63,14 +63,6 @@ function __construct($plugin_namespaces = array(), $annotation_namespaces = arra
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $plugins = $this->getDefinitions();
-    return isset($plugins[$plugin_id]) ? $plugins[$plugin_id] : NULL;
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php b/core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php
index 6da6940..d26147c 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php
@@ -31,23 +31,6 @@ public function __construct(DiscoveryInterface $decorated) {
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    list($base_plugin_id, $derivative_id) = $this->decodePluginId($plugin_id);
-
-    $plugin_definition = $this->decorated->getDefinition($base_plugin_id);
-    if (isset($plugin_definition)) {
-      $derivative_fetcher = $this->getDerivativeFetcher($base_plugin_id, $plugin_definition);
-      if ($derivative_fetcher) {
-        $plugin_definition = $derivative_fetcher->getDerivativeDefinition($derivative_id, $plugin_definition);
-      }
-    }
-
-    return $plugin_definition;
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
index aaf4743..b8075d3 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/DiscoveryInterface.php
@@ -14,17 +14,6 @@
 interface DiscoveryInterface {
 
   /**
-   * Gets a specific plugin definition.
-   *
-   * @param string $plugin_id
-   *   A plugin id.
-   *
-   * @return array|null
-   *   A plugin definition, or NULL if no definition was found for $plugin_id.
-   */
-  public function getDefinition($plugin_id);
-
-  /**
    * Gets the definition of all plugins for this type.
    *
    * @return array
diff --git a/core/lib/Drupal/Component/Plugin/Discovery/ProcessDecorator.php b/core/lib/Drupal/Component/Plugin/Discovery/ProcessDecorator.php
index fee6518..2747e4b 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/ProcessDecorator.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/ProcessDecorator.php
@@ -47,16 +47,6 @@ public function __construct(DiscoveryInterface $decorated, $process_callback) {
   }
 
   /**
-   * Implements \Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $definitions = $this->getDefinitions();
-    if (isset($definitions[$plugin_id])) {
-      return $definitions[$plugin_id];
-    }
-  }
-
-  /**
    * Implements \Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscovery.php b/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscovery.php
index de74fb5..c8dcee1 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscovery.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscovery.php
@@ -21,13 +21,6 @@ class StaticDiscovery implements DiscoveryInterface {
   protected $definitions = array();
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($base_plugin_id) {
-    return isset($this->definitions[$base_plugin_id]) ? $this->definitions[$base_plugin_id] : NULL;
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscoveryDecorator.php b/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscoveryDecorator.php
index c92ae8d..0396871 100644
--- a/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscoveryDecorator.php
+++ b/core/lib/Drupal/Component/Plugin/Discovery/StaticDiscoveryDecorator.php
@@ -41,17 +41,6 @@ public function __construct(DiscoveryInterface $decorated, $registerDefinitions
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($base_plugin_id) {
-    if (isset($this->registerDefinitions)) {
-      call_user_func($this->registerDefinitions);
-    }
-    $this->definitions += $this->decorated->getDefinitions();
-    return parent::getDefinition($base_plugin_id);
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Component/Plugin/PluginManagerBase.php b/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
index a043acc..640f65f 100644
--- a/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
+++ b/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
@@ -49,7 +49,8 @@
    * {@inheritdoc}
    */
   public function getDefinition($plugin_id) {
-    return $this->discovery->getDefinition($plugin_id);
+    $definitions = $this->discovery->getDefinitions();
+    return isset($definitions[$plugin_id]) ? $definitions[$plugin_id] : array();
   }
 
   /**
diff --git a/core/lib/Drupal/Component/Plugin/PluginManagerInterface.php b/core/lib/Drupal/Component/Plugin/PluginManagerInterface.php
index a7d74a8..ebf47b7 100644
--- a/core/lib/Drupal/Component/Plugin/PluginManagerInterface.php
+++ b/core/lib/Drupal/Component/Plugin/PluginManagerInterface.php
@@ -28,4 +28,16 @@
  * @see Drupal\Component\Plugin\PluginManagerBase
  */
 interface PluginManagerInterface extends DiscoveryInterface, FactoryInterface, MapperInterface {
+
+  /**
+   * Gets a specific plugin definition.
+   *
+   * @param string $plugin_id
+   *   A plugin id.
+   *
+   * @return array|null
+   *   A plugin definition, or NULL if no definition was found for $plugin_id.
+   */
+  public function getDefinition($plugin_id);
+
 }
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/AlterDecorator.php b/core/lib/Drupal/Core/Plugin/Discovery/AlterDecorator.php
index 8bcee3f..79395e3 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/AlterDecorator.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/AlterDecorator.php
@@ -43,15 +43,6 @@ public function __construct(DiscoveryInterface $decorated, $hook) {
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $definitions = $this->getDefinitions();
-    return isset($definitions[$plugin_id]) ? $definitions[$plugin_id] : NULL;
-  }
-
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
index a199171..1b05dcf 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
@@ -84,28 +84,6 @@ public function __construct(DiscoveryInterface $decorated, $cache_key, $cache_bi
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    // Optimize for fast access to definitions if they are already in memory.
-    if (isset($this->definitions)) {
-      // Avoid using a ternary that would create a copy of the array.
-      if (isset($this->definitions[$plugin_id])) {
-        return $this->definitions[$plugin_id];
-      }
-      else {
-        return;
-      }
-    }
-
-    $definitions = $this->getDefinitions();
-    // Avoid using a ternary that would create a copy of the array.
-    if (isset($definitions[$plugin_id])) {
-      return $definitions[$plugin_id];
-    }
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/HookDiscovery.php b/core/lib/Drupal/Core/Plugin/Discovery/HookDiscovery.php
index dce1741..2f16850 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/HookDiscovery.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/HookDiscovery.php
@@ -33,14 +33,6 @@ function __construct($hook) {
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $plugins = $this->getDefinitions();
-    return isset($plugins[$plugin_id]) ? $plugins[$plugin_id] : NULL;
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DicoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/lib/Drupal/Core/Plugin/Discovery/InfoHookDecorator.php b/core/lib/Drupal/Core/Plugin/Discovery/InfoHookDecorator.php
index 8f59989..3b022bd 100644
--- a/core/lib/Drupal/Core/Plugin/Discovery/InfoHookDecorator.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/InfoHookDecorator.php
@@ -42,14 +42,6 @@ public function __construct(DiscoveryInterface $decorated, $hook) {
   }
 
   /**
-   * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinition().
-   */
-  public function getDefinition($plugin_id) {
-    $definitions = $this->getDefinitions();
-    return isset($definitions[$plugin_id]) ? $definitions[$plugin_id] : NULL;
-  }
-
-  /**
    * Implements Drupal\Component\Plugin\Discovery\DiscoveryInterface::getDefinitions().
    */
   public function getDefinitions() {
diff --git a/core/modules/field/lib/Drupal/field/Plugin/Type/FieldType/LegacyFieldTypeDiscoveryDecorator.php b/core/modules/field/lib/Drupal/field/Plugin/Type/FieldType/LegacyFieldTypeDiscoveryDecorator.php
index 04778b3..d12d7f6 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/Type/FieldType/LegacyFieldTypeDiscoveryDecorator.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Type/FieldType/LegacyFieldTypeDiscoveryDecorator.php
@@ -45,14 +45,6 @@ public function __construct(DiscoveryInterface $decorated, ModuleHandlerInterfac
   /**
    * {@inheritdoc}
    */
-  public function getDefinition($plugin_id) {
-    $definitions = $this->getDefinitions();
-    return isset($definitions[$plugin_id]) ? $definitions[$plugin_id] : NULL;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function getDefinitions() {
     $definitions = $this->decorated->getDefinitions();