diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index 91672c1a13..5c4f2b5f3e 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -493,10 +493,12 @@ function delete_comment_meta( $comment_id, $meta_key, $meta_value = '' ) {
  * @param string $key        Optional. The meta key to retrieve. By default,
  *                           returns data for all keys.
  * @param bool   $single     Optional. Whether to return a single value.
- *                           This parameter has no effect if $key is not specified.
+ *                           This parameter has no effect if `$key` is not specified.
  *                           Default false.
- * @return mixed An array if $single is false. The value of meta data field
- *               if $single is true. False for an invalid $comment_id.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of meta data field if `$single` is true.
+ *               False for an invalid `$comment_id` (non-numeric, zero, or negative value).
+ *               An empty string if a valid but non-existing comment ID is passed.
  */
 function get_comment_meta( $comment_id, $key = '', $single = false ) {
 	return get_metadata( 'comment', $comment_id, $key, $single );
diff --git a/wp-includes/meta.php b/wp-includes/meta.php
index 8bdb9d3ae5..40b2a74159 100644
--- a/wp-includes/meta.php
+++ b/wp-includes/meta.php
@@ -497,10 +497,13 @@ function delete_metadata( $meta_type, $object_id, $meta_key, $meta_value = '', $
  * @param int    $object_id ID of the object metadata is for.
  * @param string $meta_key  Optional. Metadata key. If not specified, retrieve all metadata for
  *                          the specified object. Default empty.
- * @param bool   $single    Optional. If true, return only the first value of the specified meta_key.
- *                          This parameter has no effect if meta_key is not specified. Default false.
- * @return mixed Single metadata value, or array of values.
- *               False if there's a problem with the parameters passed to the function.
+ * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
+ *                          This parameter has no effect if `$meta_key` is not specified. Default false.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of the meta field if `$single` is true.
+ *               False for an invalid `$object_id` (non-numeric, zero, or negative value),
+ *               or if `$meta_type` is not specified.
+ *               An empty string if a valid but non-existing object ID is passed.
  */
 function get_metadata( $meta_type, $object_id, $meta_key = '', $single = false ) {
 	$value = get_metadata_raw( $meta_type, $object_id, $meta_key, $single );
@@ -521,10 +524,13 @@ function get_metadata( $meta_type, $object_id, $meta_key = '', $single = false )
  * @param int    $object_id ID of the object metadata is for.
  * @param string $meta_key  Optional. Metadata key. If not specified, retrieve all metadata for
  *                          the specified object. Default empty.
- * @param bool   $single    Optional. If true, return only the first value of the specified meta_key.
- *                          This parameter has no effect if meta_key is not specified. Default false.
- * @return mixed Single metadata value, or array of values. Null if the value does not exist.
- *               False if there's a problem with the parameters passed to the function.
+ * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
+ *                          This parameter has no effect if `$meta_key` is not specified. Default false.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of the meta field if `$single` is true.
+ *               False for an invalid `$object_id` (non-numeric, zero, or negative value),
+ *               or if `$meta_type` is not specified.
+ *               Null if the value does not exist.
  */
 function get_metadata_raw( $meta_type, $object_id, $meta_key = '', $single = false ) {
 	if ( ! $meta_type || ! is_numeric( $object_id ) ) {
@@ -608,9 +614,10 @@ function get_metadata_raw( $meta_type, $object_id, $meta_key = '', $single = fal
  *                          or any other object type with an associated meta table.
  * @param int    $object_id ID of the object metadata is for.
  * @param string $meta_key  Metadata key.
- * @param bool   $single    Optional. If true, return only the first value of the specified meta_key.
- *                          This parameter has no effect if meta_key is not specified. Default false.
- * @return mixed Single metadata value, or array of values.
+ * @param bool   $single    Optional. If true, return only the first value of the specified `$meta_key`.
+ *                          This parameter has no effect if `$meta_key` is not specified. Default false.
+ * @return mixed An array of default values if `$single` is false.
+ *               The default value of the meta field if `$single` is true.
  */
 function get_metadata_default( $meta_type, $object_id, $meta_key, $single = false ) {
 	if ( $single ) {
@@ -1401,11 +1408,12 @@ function register_meta( $object_type, $meta_key, $args, $deprecated = null ) {
  * @param mixed  $value     Current value passed to filter.
  * @param int    $object_id ID of the object metadata is for.
  * @param string $meta_key  Metadata key.
- * @param bool   $single    If true, return only the first value of the specified meta_key.
- *                          This parameter has no effect if meta_key is not specified.
+ * @param bool   $single    If true, return only the first value of the specified `$meta_key`.
+ *                          This parameter has no effect if `$meta_key` is not specified.
  * @param string $meta_type Type of object metadata is for. Accepts 'post', 'comment', 'term', 'user',
  *                          or any other object type with an associated meta table.
- * @return mixed Single metadata default, or array of defaults.
+ * @return mixed An array of default values if `$single` is false.
+ *               The default value of the meta field if `$single` is true.
  */
 function filter_default_metadata( $value, $object_id, $meta_key, $single, $meta_type ) {
 	global $wp_meta_keys;
diff --git a/wp-includes/ms-site.php b/wp-includes/ms-site.php
index 61542c1755..9a5b2ad43a 100644
--- a/wp-includes/ms-site.php
+++ b/wp-includes/ms-site.php
@@ -1084,10 +1084,12 @@ function delete_site_meta( $site_id, $meta_key, $meta_value = '' ) {
  * @param string $key     Optional. The meta key to retrieve. By default,
  *                        returns data for all keys. Default empty.
  * @param bool   $single  Optional. Whether to return a single value.
- *                        This parameter has no effect if $key is not specified.
+ *                        This parameter has no effect if `$key` is not specified.
  *                        Default false.
- * @return mixed An array if $single is false. The value of meta data field
- *               if $single is true. False for an invalid $site_id.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of meta data field if `$single` is true.
+ *               False for an invalid `$site_id` (non-numeric, zero, or negative value).
+ *               An empty string if a valid but non-existing site ID is passed.
  */
 function get_site_meta( $site_id, $key = '', $single = false ) {
 	return get_metadata( 'blog', $site_id, $key, $single );
diff --git a/wp-includes/post.php b/wp-includes/post.php
index f8ab2583ae..c04f9f78b3 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -2236,10 +2236,12 @@ function delete_post_meta( $post_id, $meta_key, $meta_value = '' ) {
  * @param string $key     Optional. The meta key to retrieve. By default,
  *                        returns data for all keys. Default empty.
  * @param bool   $single  Optional. Whether to return a single value.
- *                        This parameter has no effect if $key is not specified.
+ *                        This parameter has no effect if `$key` is not specified.
  *                        Default false.
- * @return mixed An array if $single is false. The value of the meta field
- *               if $single is true. False for an invalid $post_id.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of the meta field if `$single` is true.
+ *               False for an invalid `$post_id` (non-numeric, zero, or negative value).
+ *               An empty string if a valid but non-existing post ID is passed.
  */
 function get_post_meta( $post_id, $key = '', $single = false ) {
 	return get_metadata( 'post', $post_id, $key, $single );
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index d9dd34ccf5..94d894e442 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -1324,10 +1324,12 @@ function delete_term_meta( $term_id, $meta_key, $meta_value = '' ) {
  * @param string $key     Optional. The meta key to retrieve. By default,
  *                        returns data for all keys. Default empty.
  * @param bool   $single  Optional. Whether to return a single value.
- *                        This parameter has no effect if $key is not specified.
+ *                        This parameter has no effect if `$key` is not specified.
  *                        Default false.
- * @return mixed An array if $single is false. The value of the meta field
- *               if $single is true. False for an invalid $term_id.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of the meta field if `$single` is true.
+ *               False for an invalid `$term_id` (non-numeric, zero, or negative value).
+ *               An empty string if a valid but non-existing term ID is passed.
  */
 function get_term_meta( $term_id, $key = '', $single = false ) {
 	return get_metadata( 'term', $term_id, $key, $single );
diff --git a/wp-includes/user.php b/wp-includes/user.php
index 7aada19c9c..048bb4c511 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -1008,10 +1008,12 @@ function delete_user_meta( $user_id, $meta_key, $meta_value = '' ) {
  * @param string $key     Optional. The meta key to retrieve. By default,
  *                        returns data for all keys.
  * @param bool   $single  Optional. Whether to return a single value.
- *                        This parameter has no effect if $key is not specified.
+ *                        This parameter has no effect if `$key` is not specified.
  *                        Default false.
- * @return mixed An array if $single is false. The value of meta data field
- *               if $single is true. False for an invalid $user_id.
+ * @return mixed An array of values if `$single` is false.
+ *               The value of meta data field if `$single` is true.
+ *               False for an invalid `$user_id` (non-numeric, zero, or negative value).
+ *               An empty string if a valid but non-existing user ID is passed.
  */
 function get_user_meta( $user_id, $key = '', $single = false ) {
 	return get_metadata( 'user', $user_id, $key, $single );
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 1cdf4c2251..c621760e3e 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-alpha-50634';
+$wp_version = '5.8-alpha-50641';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.