shut up

[Bridget]

Is the "up" in "shut up" an adverb or a prepositional phrase (PP)?

"e.g.

Will you please shut up!"

[Rusty]

Is the "up" in "shut up" an adverb or a prepositional phrase (PP)?

"e.g.

Will you please shut up!"
I believe it is a prepositional phrase. When told to "shut your mouth" there is little thought about which way the jaw moves.

[Bridget]

Interesting point, Rusty.

[Rusty]

Interesting point, Rusty.
A similar phrase is "close up." A house is closed up by locking the doors. A window is sometimes closed up by pulling down or sliding sideways.