The ballast of a ship.

Any heavy material, such as gravel, sand, metal, water, etc., placed in the hold of a ship to weigh it down in the water and prevent it from…

The action or process of supplying with ballast (literally or figuratively). Also concrete: = ballast, n.

Pig-iron used as permanent ballast, usually laid upon the kelson-plates. Also attributive.

water carried in a tank or compartment and used as ballast on a boat or ship, or (later) an aircraft.

(see quots.).

Chiefly Metallurgy. An oblong mass of metal as formed by molten metal run from a furnace and allowed… a pig of iron or (rarely) lead used as…

ballast in the form of pigs of iron or (rarely) lead; cf. pig of ballast n. at sense 11f.

spec. used as ballast; esp. for a boat or balloon.

Nautical. Heavy goods taken on board ship as ballast (see quot. 1894). Cf. stiffening-order n. at compounds 2.