diff -u b/core/lib/Drupal/Core/Language/Language.php b/core/lib/Drupal/Core/Language/Language.php
--- b/core/lib/Drupal/Core/Language/Language.php
+++ b/core/lib/Drupal/Core/Language/Language.php
@@ -131,15 +131,15 @@
   /**
    * {@inheritdoc}
    */
-  public function getLangcode() {
+  public function getId() {
     return $this->id;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function setLangcode($langcode) {
-    $this->id = $langcode;
+  public function setId($id) {
+    $this->id = $id;
 
     return $this;
   }
diff -u b/core/lib/Drupal/Core/Language/LanguageInterface.php b/core/lib/Drupal/Core/Language/LanguageInterface.php
--- b/core/lib/Drupal/Core/Language/LanguageInterface.php
+++ b/core/lib/Drupal/Core/Language/LanguageInterface.php
@@ -111,20 +111,20 @@
   public function setName($name);
 
   /**
-   * Gets the language code.
+   * Gets the ID (language code).
    *
    * @return string
    */
-  public function getLangcode();
+  public function getId();
 
   /**
-   * Sets the language code.
+   * Sets the ID (language code).
    *
    * @param string $langcode
    *
    * @return $this
    */
-  public function setLangcode($langcode);
+  public function setId($id);
 
   /**
    * Gets the text direction (left-to-right or right-to-left).