argonaut

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. See paper nautilus.

Century Dictionary and Cyclopedia

1. n. One of the heroes who, according to the ancient Hellenic myth, sailed with Jason in the ship Argo to Colchis on the Euxine sea in quest of the golden fleece. This they secured, and Jason also bore back with him and his comrades to Iolcus, amid wonderful adventures, the Colchian king's daughter Medea, the enchantress.
2. n. plural Those who emigrated to California about the time of the discovery of gold there: as, the Argonauts of '49.
3. n. [lowercase] A cephalopod mollusk, known also as the paper-nautilus and paper-sailor. The common Mediterranean species, Argonauta argo, was fabled to carry its velamentous arms erect as sails, and thereby to be wafted by the winds. The arms are in fact commonly carried appressed to the shell, and progression is effected chiefly backward, as with other cuttlefishes, by the ejection of water through the siphon.

Wiktionary

1. n. A pelagic octopus of the genus Argonauta.
2. n. An adventurer on a dangerous but rewarding quest.

GNU Webster's 1913

1. n. Any one of the legendary Greek heroes who sailed with Jason, in the Argo, in quest of the Golden Fleece.
2. n. (Zoöl.) A cephalopod of the genus Argonauta.
3. n. United States One of those who went to California in search of gold shortly after it was discovered there in 1848.

WordNet 3.0

1. n. someone engaged in a dangerous but potentially rewarding adventure
2. n. cephalopod mollusk of warm seas whose females have delicate papery spiral shells
3. n. (Greek mythology) one of the heroes who sailed with Jason in search of the Golden Fleece