diff --git a/src/wp-admin/edit-form-advanced.php b/src/wp-admin/edit-form-advanced.php
index 20b62af216..4a41ab6659 100644
--- a/src/wp-admin/edit-form-advanced.php
+++ b/src/wp-admin/edit-form-advanced.php
@@ -376,7 +376,7 @@ if ( 'post' == $post_type ) {
 
 	if ( current_theme_supports( 'post-thumbnails' ) && post_type_supports( 'post', 'thumbnail' ) ) {
 		$publish_box .= '<li>' . sprintf(
-			/* translators: %s: Featured Image. */
+			/* translators: %s: Featured image. */
 			__( '<strong>%s</strong> &mdash; This allows you to associate an image with your post without inserting it. This is usually useful only if your theme makes use of the image as a post thumbnail on the home page, a custom header, etc.' ),
 			esc_html( $post_type_object->labels->featured_image )
 		) . '</li>';
diff --git a/src/wp-admin/includes/post.php b/src/wp-admin/includes/post.php
index 279a86567e..0ad9bcdaf0 100644
--- a/src/wp-admin/includes/post.php
+++ b/src/wp-admin/includes/post.php
@@ -1517,7 +1517,7 @@ function _wp_post_thumbnail_html( $thumbnail_id = null, $post = null ) {
 		$size = isset( $_wp_additional_image_sizes['post-thumbnail'] ) ? 'post-thumbnail' : array( 266, 266 );
 
 		/**
-		 * Filters the size used to display the post thumbnail image in the 'Featured Image' meta box.
+		 * Filters the size used to display the post thumbnail image in the 'Featured image' meta box.
 		 *
 		 * Note: When a theme adds 'post-thumbnail' support, a special 'post-thumbnail'
 		 * image size is registered, which differs from the 'thumbnail' image size
diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 0e09610521..3b038c1163 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -1646,7 +1646,7 @@ function _post_type_meta_capabilities( $capabilities = null ) {
  * - `insert_into_item` - Label for the media frame button. Default is 'Insert into post' / 'Insert into page'.
  * - `uploaded_to_this_item` - Label for the media frame filter. Default is 'Uploaded to this post' /
  *                           'Uploaded to this page'.
- * - `featured_image` - Label for the Featured Image meta box title. Default is 'Featured Image'.
+ * - `featured_image` - Label for the featured image meta box title. Default is 'Featured image'.
  * - `set_featured_image` - Label for setting the featured image. Default is 'Set featured image'.
  * - `remove_featured_image` - Label for removing the featured image. Default is 'Remove featured image'.
  * - `use_featured_image` - Label in the media frame for using a featured image. Default is 'Use as featured image'.
@@ -1704,7 +1704,7 @@ function get_post_type_labels( $post_type_object ) {
 		'attributes'               => array( __( 'Post Attributes' ), __( 'Page Attributes' ) ),
 		'insert_into_item'         => array( __( 'Insert into post' ), __( 'Insert into page' ) ),
 		'uploaded_to_this_item'    => array( __( 'Uploaded to this post' ), __( 'Uploaded to this page' ) ),
-		'featured_image'           => array( _x( 'Featured Image', 'post' ), _x( 'Featured Image', 'page' ) ),
+		'featured_image'           => array( _x( 'Featured image', 'post' ), _x( 'Featured image', 'page' ) ),
 		'set_featured_image'       => array( _x( 'Set featured image', 'post' ), _x( 'Set featured image', 'page' ) ),
 		'remove_featured_image'    => array( _x( 'Remove featured image', 'post' ), _x( 'Remove featured image', 'page' ) ),
 		'use_featured_image'       => array( _x( 'Use as featured image', 'post' ), _x( 'Use as featured image', 'page' ) ),
diff --git a/tests/qunit/index.html b/tests/qunit/index.html
index 9b05fb6f78..46b8403861 100644
--- a/tests/qunit/index.html
+++ b/tests/qunit/index.html
@@ -48,7 +48,7 @@
 		<script src="../../build/wp-includes/js/mediaelement/wp-mediaelement.js"></script>
 		<script src="../../build/wp-includes/js/dist/i18n.js"></script>
 		<script>
-			window._wpMediaViewsL10n = {"mediaFrameDefaultTitle":"Media","url":"URL","addMedia":"Add Media","search":"Search","select":"Select","cancel":"Cancel","update":"Update","replace":"Replace","remove":"Remove","back":"Back","selected":"%d selected","dragInfo":"Drag and drop to reorder media files.","uploadFilesTitle":"Upload Files","uploadImagesTitle":"Upload Images","mediaLibraryTitle":"Media Library","insertMediaTitle":"Add Media","createNewGallery":"Create a new gallery","createNewPlaylist":"Create a new playlist","createNewVideoPlaylist":"Create a new video playlist","returnToLibrary":"\u2190 Return to library","allMediaItems":"All media items","allDates":"All dates","noItemsFound":"No items found.","insertIntoPost":"Insert into post","unattached":"Unattached","mine":"Mine","trash":"Trash","uploadedToThisPost":"Uploaded to this post","warnDelete":"You are about to permanently delete this item from your site.\nThis action cannot be undone.\n 'Cancel' to stop, 'OK' to delete.","warnBulkDelete":"You are about to permanently delete these items from your site.\nThis action cannot be undone.\n 'Cancel' to stop, 'OK' to delete.","warnBulkTrash":"You are about to trash these items.\n  'Cancel' to stop, 'OK' to delete.","bulkSelect":"Bulk Select","trashSelected":"Move to Trash","restoreSelected":"Restore from Trash","deletePermanently":"Delete Permanently","apply":"Apply","filterByDate":"Filter by date","filterByType":"Filter by type","searchMediaLabel":"Search Media","searchMediaPlaceholder":"Search media items...","mediaFound":"Number of media items found: %d","mediaFoundHasMoreResults":"Number of media items displayed: %d. Scroll the page for more results.","noMedia":"No media items found.","noMediaTryNewSearch":"No media items found. Try a different search.","attachmentDetails":"Attachment Details","insertFromUrlTitle":"Insert from URL","setFeaturedImageTitle":"Featured Image","setFeaturedImage":"Set featured image","createGalleryTitle":"Create Gallery","editGalleryTitle":"Edit Gallery","cancelGalleryTitle":"\u2190 Cancel Gallery","insertGallery":"Insert gallery","updateGallery":"Update gallery","addToGallery":"Add to gallery","addToGalleryTitle":"Add to Gallery","reverseOrder":"Reverse order","imageDetailsTitle":"Image Details","imageReplaceTitle":"Replace Image","imageDetailsCancel":"Cancel Edit","editImage":"Edit Image","chooseImage":"Choose Image","selectAndCrop":"Select and Crop","skipCropping":"Skip Cropping","cropImage":"Crop Image","cropYourImage":"Crop your image","cropping":"Cropping\u2026","suggestedDimensions":"Suggested image dimensions: %1$s by %2$s pixels.","cropError":"There has been an error cropping your image.","audioDetailsTitle":"Audio Details","audioReplaceTitle":"Replace Audio","audioAddSourceTitle":"Add Audio Source","audioDetailsCancel":"Cancel Edit","videoDetailsTitle":"Video Details","videoReplaceTitle":"Replace Video","videoAddSourceTitle":"Add Video Source","videoDetailsCancel":"Cancel Edit","videoSelectPosterImageTitle":"Select Poster Image","videoAddTrackTitle":"Add Subtitles","playlistDragInfo":"Drag and drop to reorder tracks.","createPlaylistTitle":"Create Audio Playlist","editPlaylistTitle":"Edit Audio Playlist","cancelPlaylistTitle":"\u2190 Cancel Audio Playlist","insertPlaylist":"Insert audio playlist","updatePlaylist":"Update audio playlist","addToPlaylist":"Add to audio playlist","addToPlaylistTitle":"Add to Audio Playlist","videoPlaylistDragInfo":"Drag and drop to reorder videos.","createVideoPlaylistTitle":"Create Video Playlist","editVideoPlaylistTitle":"Edit Video Playlist","cancelVideoPlaylistTitle":"\u2190 Cancel Video Playlist","insertVideoPlaylist":"Insert video playlist","updateVideoPlaylist":"Update video playlist","addToVideoPlaylist":"Add to video playlist","addToVideoPlaylistTitle":"Add to Video Playlist","filterAttachments":"Filter Media","attachmentsList":"Media list","settings":{"tabs":[],"tabUrl":"http:\/\/build.wordpress-develop.test\/wp-admin\/media-upload.php?chromeless=1","mimeTypes":{"image":"Images","audio":"Audio","video":"Video","application\/msword,application\/vnd.openxmlformats-officedocument.wordprocessingml.document,application\/vnd.ms-word.document.macroEnabled.12,application\/vnd.ms-word.template.macroEnabled.12,application\/vnd.oasis.opendocument.text,application\/vnd.apple.pages,application\/pdf,application\/vnd.ms-xpsdocument,application\/oxps,application\/rtf,application\/wordperfect,application\/octet-stream":"Documents","application\/vnd.apple.numbers,application\/vnd.oasis.opendocument.spreadsheet,application\/vnd.ms-excel,application\/vnd.openxmlformats-officedocument.spreadsheetml.sheet,application\/vnd.ms-excel.sheet.macroEnabled.12,application\/vnd.ms-excel.sheet.binary.macroEnabled.12":"Spreadsheets","application\/x-gzip,application\/rar,application\/x-tar,application\/zip,application\/x-7z-compressed":"Archives"},"captions":true,"nonce":{"sendToEditor":"078fccea44"},"post":{"id":7734,"nonce":"b81d45d05c","featuredImageId":-1},"defaultProps":{"link":"","align":"","size":""},"attachmentCounts":{"audio":1,"video":1},"oEmbedProxyUrl":"http:\/\/build.wordpress-develop.test\/wp-json\/oembed\/1.0\/proxy","embedExts":["mp3","ogg","flac","m4a","wav","mp4","m4v","webm","ogv","flv"],"embedMimes":{"mp3":"audio\/mpeg","ogg":"audio\/ogg","flac":"audio\/flac","m4a":"audio\/mpeg","wav":"audio\/wav","mp4":"video\/mp4","m4v":"video\/mp4","webm":"video\/webm","ogv":"video\/ogg","flv":"video\/x-flv"},"contentWidth":580,"months":[{"year":"2019","month":"10","text":"October 2019"},{"year":"2019","month":"9","text":"September 2019"},{"year":"2019","month":"7","text":"July 2019"},{"year":"2019","month":"6","text":"June 2019"},{"year":"2014","month":"1","text":"January 2014"},{"year":"2013","month":"12","text":"December 2013"},{"year":"2013","month":"9","text":"September 2013"},{"year":"2013","month":"4","text":"April 2013"},{"year":"2013","month":"3","text":"March 2013"},{"year":"2012","month":"7","text":"July 2012"},{"year":"2012","month":"6","text":"June 2012"},{"year":"2011","month":"7","text":"July 2011"},{"year":"2011","month":"1","text":"January 2011"}],"mediaTrash":0}};
+			window._wpMediaViewsL10n = {"mediaFrameDefaultTitle":"Media","url":"URL","addMedia":"Add Media","search":"Search","select":"Select","cancel":"Cancel","update":"Update","replace":"Replace","remove":"Remove","back":"Back","selected":"%d selected","dragInfo":"Drag and drop to reorder media files.","uploadFilesTitle":"Upload Files","uploadImagesTitle":"Upload Images","mediaLibraryTitle":"Media Library","insertMediaTitle":"Add Media","createNewGallery":"Create a new gallery","createNewPlaylist":"Create a new playlist","createNewVideoPlaylist":"Create a new video playlist","returnToLibrary":"\u2190 Return to library","allMediaItems":"All media items","allDates":"All dates","noItemsFound":"No items found.","insertIntoPost":"Insert into post","unattached":"Unattached","mine":"Mine","trash":"Trash","uploadedToThisPost":"Uploaded to this post","warnDelete":"You are about to permanently delete this item from your site.\nThis action cannot be undone.\n 'Cancel' to stop, 'OK' to delete.","warnBulkDelete":"You are about to permanently delete these items from your site.\nThis action cannot be undone.\n 'Cancel' to stop, 'OK' to delete.","warnBulkTrash":"You are about to trash these items.\n  'Cancel' to stop, 'OK' to delete.","bulkSelect":"Bulk Select","trashSelected":"Move to Trash","restoreSelected":"Restore from Trash","deletePermanently":"Delete Permanently","apply":"Apply","filterByDate":"Filter by date","filterByType":"Filter by type","searchMediaLabel":"Search Media","searchMediaPlaceholder":"Search media items...","mediaFound":"Number of media items found: %d","mediaFoundHasMoreResults":"Number of media items displayed: %d. Scroll the page for more results.","noMedia":"No media items found.","noMediaTryNewSearch":"No media items found. Try a different search.","attachmentDetails":"Attachment Details","insertFromUrlTitle":"Insert from URL","setFeaturedImageTitle":"Featured image","setFeaturedImage":"Set featured image","createGalleryTitle":"Create Gallery","editGalleryTitle":"Edit Gallery","cancelGalleryTitle":"\u2190 Cancel Gallery","insertGallery":"Insert gallery","updateGallery":"Update gallery","addToGallery":"Add to gallery","addToGalleryTitle":"Add to Gallery","reverseOrder":"Reverse order","imageDetailsTitle":"Image Details","imageReplaceTitle":"Replace Image","imageDetailsCancel":"Cancel Edit","editImage":"Edit Image","chooseImage":"Choose Image","selectAndCrop":"Select and Crop","skipCropping":"Skip Cropping","cropImage":"Crop Image","cropYourImage":"Crop your image","cropping":"Cropping\u2026","suggestedDimensions":"Suggested image dimensions: %1$s by %2$s pixels.","cropError":"There has been an error cropping your image.","audioDetailsTitle":"Audio Details","audioReplaceTitle":"Replace Audio","audioAddSourceTitle":"Add Audio Source","audioDetailsCancel":"Cancel Edit","videoDetailsTitle":"Video Details","videoReplaceTitle":"Replace Video","videoAddSourceTitle":"Add Video Source","videoDetailsCancel":"Cancel Edit","videoSelectPosterImageTitle":"Select Poster Image","videoAddTrackTitle":"Add Subtitles","playlistDragInfo":"Drag and drop to reorder tracks.","createPlaylistTitle":"Create Audio Playlist","editPlaylistTitle":"Edit Audio Playlist","cancelPlaylistTitle":"\u2190 Cancel Audio Playlist","insertPlaylist":"Insert audio playlist","updatePlaylist":"Update audio playlist","addToPlaylist":"Add to audio playlist","addToPlaylistTitle":"Add to Audio Playlist","videoPlaylistDragInfo":"Drag and drop to reorder videos.","createVideoPlaylistTitle":"Create Video Playlist","editVideoPlaylistTitle":"Edit Video Playlist","cancelVideoPlaylistTitle":"\u2190 Cancel Video Playlist","insertVideoPlaylist":"Insert video playlist","updateVideoPlaylist":"Update video playlist","addToVideoPlaylist":"Add to video playlist","addToVideoPlaylistTitle":"Add to Video Playlist","filterAttachments":"Filter Media","attachmentsList":"Media list","settings":{"tabs":[],"tabUrl":"http:\/\/build.wordpress-develop.test\/wp-admin\/media-upload.php?chromeless=1","mimeTypes":{"image":"Images","audio":"Audio","video":"Video","application\/msword,application\/vnd.openxmlformats-officedocument.wordprocessingml.document,application\/vnd.ms-word.document.macroEnabled.12,application\/vnd.ms-word.template.macroEnabled.12,application\/vnd.oasis.opendocument.text,application\/vnd.apple.pages,application\/pdf,application\/vnd.ms-xpsdocument,application\/oxps,application\/rtf,application\/wordperfect,application\/octet-stream":"Documents","application\/vnd.apple.numbers,application\/vnd.oasis.opendocument.spreadsheet,application\/vnd.ms-excel,application\/vnd.openxmlformats-officedocument.spreadsheetml.sheet,application\/vnd.ms-excel.sheet.macroEnabled.12,application\/vnd.ms-excel.sheet.binary.macroEnabled.12":"Spreadsheets","application\/x-gzip,application\/rar,application\/x-tar,application\/zip,application\/x-7z-compressed":"Archives"},"captions":true,"nonce":{"sendToEditor":"078fccea44"},"post":{"id":7734,"nonce":"b81d45d05c","featuredImageId":-1},"defaultProps":{"link":"","align":"","size":""},"attachmentCounts":{"audio":1,"video":1},"oEmbedProxyUrl":"http:\/\/build.wordpress-develop.test\/wp-json\/oembed\/1.0\/proxy","embedExts":["mp3","ogg","flac","m4a","wav","mp4","m4v","webm","ogv","flv"],"embedMimes":{"mp3":"audio\/mpeg","ogg":"audio\/ogg","flac":"audio\/flac","m4a":"audio\/mpeg","wav":"audio\/wav","mp4":"video\/mp4","m4v":"video\/mp4","webm":"video\/webm","ogv":"video\/ogg","flv":"video\/x-flv"},"contentWidth":580,"months":[{"year":"2019","month":"10","text":"October 2019"},{"year":"2019","month":"9","text":"September 2019"},{"year":"2019","month":"7","text":"July 2019"},{"year":"2019","month":"6","text":"June 2019"},{"year":"2014","month":"1","text":"January 2014"},{"year":"2013","month":"12","text":"December 2013"},{"year":"2013","month":"9","text":"September 2013"},{"year":"2013","month":"4","text":"April 2013"},{"year":"2013","month":"3","text":"March 2013"},{"year":"2012","month":"7","text":"July 2012"},{"year":"2012","month":"6","text":"June 2012"},{"year":"2011","month":"7","text":"July 2011"},{"year":"2011","month":"1","text":"January 2011"}],"mediaTrash":0}};
 		</script>
 		<script src="../../build/wp-includes/js/media-views.js"></script>
 		<script src="../../build/wp-includes/js/media-editor.js"></script>