1. A large cask; an oblong vessel bulging in the middle, like a pipe or puncheon, and girt with hoops; a wine cask.
2. A fermenting vat.
3. A certain measure for liquids, as for wine, equal to two pipes, four hogsheads, or 252 gallons. In different countries, the tun differs in quantity.
4. A weight of 2,240 pounds. See ton.
5. An indefinite large quantity. A tun of man in thy large bulk is writ. (Dryden)
6. A drunkard; so called humorously, or in contempt.
7. (Science: zoology) Any shell belonging to dolium and allied genera; called also tun-shell.
Origin: AS. Tunne. See Ton a weight.