- argonaut - someone engaged in a dangerous but potentially rewarding adventure
--1 is a kind of adventurer, venturer
- Argonaut - (Greek mythology) one of the heroes who sailed with Jason on the Argo in search of the Golden Fleece
--2 is a kind of fictional character, fictitious character, character
- paper nautilus, nautilus, Argonaut, Argonauta argo - cephalopod mollusk of warm seas whose females have delicate papery spiral shells
--3 is a kind of octopod
--3 is a member of Argonauta, genus Argonauta - Argonaut - (Greek mythology) one of the heroes who sailed with Jason on the Argo in search of the Golden Fleece