Definition of "nautilus" in English

noun

1. A marine mollusc, of the family Nautilidae native to the Pacific Ocean and Indian Ocean, which has tentacles and a spiral shell with a series of air-filled chambers, of which Nautilus is the type genus.

2. A kind of diving bell that sinks or rises by means of compressed air.

3. (inexact) A paper nautilus (actually an octopus).