WordPress: Rename the Excerpt Editing Area Label

It's true that when we talk about an excerpt, nobody understands what it refers to.
To change the title of this editing area, just use the following snippet of code:

add_filter( 'gettext', 'wpse22764_gettext', 10, 2 );
function wpse22764_gettext( $translation, $original )
{
if ( 'Excerpt' == $original ) {
return 'Sous-titre';
}else{
$pos = strpos($original, 'Excerpts are optional hand-crafted summaries of your');
if ($pos !== false) {
return  'Sous-titre affiché dans les push.';
}
}
return $translation;
}