Definition of Nautilus

Noun: nautilus (nautiluses,nautili) no-ti-lus

A submarine that is propelled by nuclear power
- nuclear submarine, nuclear-powered submarine
Cephalopod mollusk of warm seas whose females have delicate papery spiral shells
- paper nautilus, Argonaut, Argonauta argo
Cephalopod of the Indian and Pacific oceans having a spiral shell with pale pearly partitions
- chambered nautilus, pearly nautilus