To make something flat or flatter.
To press one's body tightly against a surface, such as a wall or floor, especially in order to avoid being seen or harmed.
To knock down or lay low.
To become flat or flatter; to plateau.
To be knocked down or laid low.
To lower by a semitone.
To make vapid or insipid; to render stale.
To reduce (a data structure) to one that has fewer dimensions, e.g. a 2×2 array into a list of four elements.
To combine (separate layers) into a single image.