n. The fruit of the oak; a one-celled, one-seeded, coriaceous, rounded or elongated nut, the base of which is surrounded by an indurated scaly cup.n. Nautical, a small ornamental piece of wood, of a conical or globular shape, sometimes fixed on the point of the spindle above the vane, on a masthead, to keep the vane from being blown off.n. Any similar ornamental tip.n. Same as acorn-shell, 2.