Vestlet \Vest"let\, n. [Dim. of vest.] (Zo["o]l.) Any one of several species of actinians belonging to the genus {Cerianthus}. These animals have a long, smooth body tapering to the base, and two separate circles of tentacles around the mouth. They form a tough, flexible, feltlike tube with a smooth internal lining, in which they dwell, whence the name.