(transitive) To make something flat or flatter.

(reflexive) To press one's body tightly against a surface, such as a wall or floor, especially in order to avoid being seen or harmed.

(transitive) To knock down or lay low.

(intransitive) To become flat or flatter; to plateau.

(intransitive) To be knocked down or laid low.

(music) To lower by a semitone.

To make vapid or insipid; to render stale.

(programming, transitive) To reduce (a data structure) to one that has fewer dimensions, e.g. a 2×2 array into a list of four elements.

(computer graphics, transitive) To combine (separate layers) into a single image.