ARGONAUT'A, noun [See Argonaut.] A genus of shell-fish, of the order of vermes testacea. The shell consists of one spiral involuted valve. There are several species; one of which is the Argo, with a subdentated carina, the famous nautilus, which, when it sails, extends two of its arms, spreading a membrane, which serves for a sail, and six other arms are thrown out, for rowing or steering.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI