diff --git a/wp-includes/comment.php b/wp-includes/comment.php
index 0da7d13e42..f3cdb9cc0f 100644
--- a/wp-includes/comment.php
+++ b/wp-includes/comment.php
@@ -450,7 +450,7 @@ function get_comment_count( $post_id = 0 ) {
  * @param int $comment_id Comment ID.
  * @param string $meta_key Metadata name.
  * @param mixed $meta_value Metadata value.
- * @param bool $unique Optional, default is false. Whether the same key should not be added.
+ * @param bool $unique Optional. Whether the same key should not be added. Default false.
  * @return int|bool Meta ID on success, false on failure.
  */
 function add_comment_meta( $comment_id, $meta_key, $meta_value, $unique = false ) {
@@ -484,7 +484,7 @@ function delete_comment_meta( $comment_id, $meta_key, $meta_value = '' ) {
  *
  * @param int $comment_id Comment ID.
  * @param string $key Optional. The meta key to retrieve. By default, returns data for all keys.
- * @param bool $single Whether to return a single value.
+ * @param bool $single Optional. Whether to return a single value. Default false.
  * @return mixed Will be an array if $single is false. Will be value of meta data field if $single
  *  is true.
  */
@@ -506,7 +506,7 @@ function get_comment_meta( $comment_id, $key = '', $single = false ) {
  * @param int $comment_id Comment ID.
  * @param string $meta_key Metadata key.
  * @param mixed $meta_value Metadata value.
- * @param mixed $prev_value Optional. Previous value to check before removing.
+ * @param mixed $prev_value Optional. Previous value to check before updating. Default empty.
  * @return int|bool Meta ID if the key didn't exist, true on successful update, false on failure.
  */
 function update_comment_meta( $comment_id, $meta_key, $meta_value, $prev_value = '' ) {
diff --git a/wp-includes/meta.php b/wp-includes/meta.php
index 99df89697f..73f253a840 100644
--- a/wp-includes/meta.php
+++ b/wp-includes/meta.php
@@ -149,7 +149,7 @@ function add_metadata( $meta_type, $object_id, $meta_key, $meta_value, $unique =
  * @param string $meta_key   Metadata key.
  * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
  * @param mixed  $prev_value Optional. If specified, only update existing metadata entries
- *                           with this value. Otherwise, update all entries.
+ *                           with this value. Otherwise, update all entries. Default empty.
  * @return int|bool The new meta field ID if a field with the given key didn't exist and was
  *                  therefore added, true on successful update, false on failure.
  */
diff --git a/wp-includes/ms-site.php b/wp-includes/ms-site.php
index 186237430e..947f0e0301 100644
--- a/wp-includes/ms-site.php
+++ b/wp-includes/ms-site.php
@@ -1096,7 +1096,7 @@ function get_site_meta( $site_id, $key = '', $single = false ) {
  * @param int    $site_id    Site ID.
  * @param string $meta_key   Metadata key.
  * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
- * @param mixed  $prev_value Optional. Previous value to check before removing.
+ * @param mixed  $prev_value Optional. Previous value to check before updating.
  *                           Default empty.
  * @return int|bool Meta ID if the key didn't exist, true on successful update,
  *                  false on failure.
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 2f547a4cf9..262f986221 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -2136,7 +2136,7 @@ function get_post_meta( $post_id, $key = '', $single = false ) {
  * @param int    $post_id    Post ID.
  * @param string $meta_key   Metadata key.
  * @param mixed  $meta_value Metadata value. Must be serializable if non-scalar.
- * @param mixed  $prev_value Optional. Previous value to check before updating.
+ * @param mixed  $prev_value Optional. Previous value to check before updating. Default empty.
  * @return int|bool The new meta field ID if a field with the given key didn't exist and was
  *                  therefore added, true on successful update, false on failure.
  */
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index abb92f2e93..0d257c0e7f 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -1246,8 +1246,8 @@ function delete_term_meta( $term_id, $meta_key, $meta_value = '' ) {
  *
  * @param int    $term_id Term ID.
  * @param string $key     Optional. The meta key to retrieve. If no key is provided, fetches all metadata for the term.
- * @param bool   $single  Whether to return a single value. If false, an array of all values matching the
- *                        `$term_id`/`$key` pair will be returned. Default: false.
+ * @param bool   $single  Optional. Whether to return a single value. If false, an array of all values matching the
+ *                        `$term_id`/`$key` pair will be returned. Default false.
  * @return mixed If `$single` is false, an array of metadata values. If `$single` is true, a single metadata value.
  */
 function get_term_meta( $term_id, $key = '', $single = false ) {
@@ -1266,7 +1266,7 @@ function get_term_meta( $term_id, $key = '', $single = false ) {
  * @param int    $term_id    Term ID.
  * @param string $meta_key   Metadata key.
  * @param mixed  $meta_value Metadata value.
- * @param mixed  $prev_value Optional. Previous value to check before removing.
+ * @param mixed  $prev_value Optional. Previous value to check before updating. Default empty.
  * @return int|WP_Error|bool Meta ID if the key didn't previously exist. True on successful update.
  *                           WP_Error when term_id is ambiguous between taxonomies. False on failure.
  */
diff --git a/wp-includes/user.php b/wp-includes/user.php
index 6c6f87eced..2223e7a40e 100644
--- a/wp-includes/user.php
+++ b/wp-includes/user.php
@@ -821,7 +821,7 @@ function delete_user_meta( $user_id, $meta_key, $meta_value = '' ) {
  *
  * @param int    $user_id User ID.
  * @param string $key     Optional. The meta key to retrieve. By default, returns data for all keys.
- * @param bool   $single  Whether to return a single value.
+ * @param bool   $single  Optional. Whether to return a single value. Default false.
  * @return mixed Will be an array if $single is false. Will be value of meta data field if $single is true.
  */
 function get_user_meta( $user_id, $key = '', $single = false ) {
@@ -842,7 +842,7 @@ function get_user_meta( $user_id, $key = '', $single = false ) {
  * @param int    $user_id    User ID.
  * @param string $meta_key   Metadata key.
  * @param mixed  $meta_value Metadata value.
- * @param mixed  $prev_value Optional. Previous value to check before removing.
+ * @param mixed  $prev_value Optional. Previous value to check before updating. Default empty.
  * @return int|bool Meta ID if the key didn't exist, true on successful update, false on failure.
  */
 function update_user_meta( $user_id, $meta_key, $meta_value, $prev_value = '' ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 466e6cf811..b814c6c17d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-47609';
+$wp_version = '5.5-alpha-47610';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.