Meaning

noun marine mollusks having a rough irregular shell; found on the sea bed mostly in coastal waters

noun edible body of any of numerous oysters

noun a small muscle on each side of the back of a fowl

originFrom Middle English oystre, from Old English ostre, reinforced or superseded by Anglo-Norman oistre, which is from Old French oistre, uistre (compare modern French huître); both lines (Old English and Old French) from Latin ostrea, from Ancient Greek ὄστρεον (óstreon). Doublet of ostro (“a purple dye”).

Etymology from Wiktionary, CC BY-SA 3.0