early 14c., from Old French oistre (Modern French huître), from Latin ostrea, plural or fem. of ostreum "oyster," from Greek ostreon, from PIE *ost- "bone" (see osseous). Related to Greek ostrakon "hard shell" and to osteon "bone."
Why then the world's mine Oyster, which I, with sword will open. [Shakespeare, "The Merry Wives of Windsor," II.ii.2]