WordNet sense 1 (a submarine that is propelled by nuclear power):

nuclear-powered submarine, nuclear submarine

WordNet sense 2 (cephalopod mollusk of warm seas whose females have delicate papery spiral shells):

argonaut, paper nautilus, Argonauta argo

WordNet sense 3 (cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions):

chambered nautilus, pearly nautilus