pwc

As a noun motorboat

is any vessel driven by an engine (either inboard or outboard), but especially a small one.

As a verb motorboat

is to place one's head between a woman's breasts and make the sound of a motorboat with one's lips whilst moving the head from side to side.

As an initialism PWC is

personal Water Craft.

As an initialism pwc is

personal]] water [[craft|craft.