1. A large cask; an oblong vessel bulging in the middle, like a pipe or puncheon, and girt with hoops; a wine cask.
2. (Brewing)
Defn: 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. (Com.)
Defn: A weight of 2,240 pounds. See Ton. [R.]
5. An indefinite large quantity. Shak. A tun of man in thy large bulk is writ. Dryden.
6. A drunkard; — so called humorously, or in contempt.
7. (Zoöl.)
Defn: Any shell belonging to Dolium and allied genera; — called also tun-shell.