any of several species of edible marine invertebrate animal withs that have a rough irregular hinged shell that is and are found in coastal waters or estuaries: family Ostreidae
a pinkish white colour, sometimes with a greyish tone
a small mass of meat contained in a hollow of the pelvic bone on each side of the back of a fowl
the world is one's oyster
one has many opportunities [derived from the exchange between Sir John Falstaff and Pistol in Shakespeare's The Merry Wives of Windsor (1597) II.ii.4 ‘[Sir John] I will not lend thee a penny … [Pistol] Why then, the world's mine oyster, which I with sword will open.’]
[Middle English oistre via French and Latin from Greek ostreon]