motor + boat
Wikipedia motorboat (plural motorboats)
- (nautical) Any vessel driven by an engine (either inboard or outboard), but especially a small one.
See also 
motorboat (third-person singular simple present motorboats, present participle motorboating, simple past and past participle motorboated)
- (informal) 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