is·let \ˈīlə̇t, usu -ə̇d.+V\noun (-s) Etymology: Middle French islette, from isle + -ette 1.: a small island : isle 2.: something resembling a small island especially in its isolation or elevation: a.: island 2a b.chiefly Britain: island 2c c.: a small isolated mass of one type of tissue within a different type; specifically: islet of langerhans