The Collaborative International Dictionary of English v.0.48:

Sack \Sack\, n. [OE. sak, sek, AS. sacc, saecc, L. saccus, Gr.
   sa`kkos from Heb. sak; cf. F. sac, from the Latin. Cf. Sac,
   Satchel, Sack to plunder.]
   1. A bag for holding and carrying goods of any kind; a
      receptacle made of some kind of pliable material, as
      cloth, leather, and the like; a large pouch.
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   2. A measure of varying capacity, according to local usage
      and the substance. The American sack of salt is 215
      pounds; the sack of wheat, two bushels. --McElrath.
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   3. [Perhaps a different word.] Originally, a loosely hanging
      garment for women, worn like a cloak about the shoulders,
      and serving as a decorative appendage to the gown; now, an
      outer garment with sleeves, worn by women; as, a dressing
      sack. [Written also sacque.]
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   4. A sack coat; a kind of coat worn by men, and extending
      from top to bottom without a cross seam.
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   5. (Biol.) See 2d Sac, 2.
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   Sack bearer (Zool.). See Basket worm, under Basket.

   Sack tree (Bot.), an East Indian tree (Antiaris
      saccidora) which is cut into lengths, and made into sacks
      by turning the bark inside out, and leaving a slice of the
      wood for a bottom.

   To give the sack to or get the sack, to discharge, or be
      discharged, from employment; to jilt, or be jilted.
      [Slang]

   To hit the sack, to go to bed. [Slang]
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