Nautilus

n.	1.	(Zool.) The only existing genus of tetrabranchiate cephalopods. About four species are found living in the tropical Pacific, but many other species are found fossil. The shell is spiral, symmetrical, and chambered, or divided into several cavities by simple curved partitions, which are traversed and connected together by a continuous and nearly central tube or siphuncle. See Tetrabranchiata.
	2.	The argonaut; - also called paper nautilus. See Argonauta, and Paper nautilus, under Paper.
	3.	A variety of diving bell, the lateral as well as vertical motions of which are controlled, by the occupants.

Noun	1.	nautilus - a submarine that is propelled by nuclear power Synonyms: nuclear submarine, nuclear-powered submarine
	2.	nautilus - cephalopod mollusk of warm seas whose females have delicate papery spiral shells Synonyms: Argonauta argo, paper nautilus, Argonaut
	3.	nautilus - cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions Synonyms: chambered nautilus, pearly nautilus

nuclear submarine, nuclear-powered submarine, pigboat, sub, submarine, U-boat