Index: src/wp-includes/class-wp-locale.php
===================================================================
--- src/wp-includes/class-wp-locale.php	(revision 42360)
+++ src/wp-includes/class-wp-locale.php	(working copy)
@@ -271,7 +271,7 @@
 	 *
 	 * @since 2.1.0
 	 *
-	 * @param string $weekday_name
+	 * @param string $weekday_name Full translated weekday word
 	 * @return string
 	 */
 	public function get_weekday_initial( $weekday_name ) {