1. (Science: botany) A dry one-seeded fruit which is indehiscent (i.e., it does not split open along a definite seam at maturity). Among the true nuts are the acorn, chestnut, hazelnut, beech, filbert, etc). Others that are not botanically true nuts are the peanut, cashew, coconut, litchi, pistachio, almond and the walnut.
3. The tumbler of a gunlock.
4. A projection on each side of the shank of an anchor, to secure the stock in Place. Check nut, jam nut, lock nut, a nut which is screwed up tightly against another nut on the same bolt or screw, in order to prevent accidental unscrewing of the first nut. Nut buoy. See Buoy. Nut coal, screened coal of a size smaller than stove coal and larger than pea coal; called also chestnut coal.