It was the name of the ship that Jason and the argonauts sailed in to liberate the Golden Fleece against impossible odds.
"sailor of the Argo," 1580s (implied in argonautic), from Argo + Greek nautes "sailor" (see naval). Adventurers in the California Gold Rush of 1848 were called argonauts (because they sought the golden fleece) by those who stayed home.
In classical mythology, the companions of Jason in the quest for the Golden Fleece. Their ship was the Argo.
Note: Naut means “sailor” in Greek and is the root of our word nautical. Today, the word is used to coin terms such as astronaut and aquanaut.