sac /ˈsæk/
  囊;液囊;氣囊
  Sac, n.  O.Eng. Law The privilege formerly enjoyed by the lord of a manor, of holding courts, trying causes, and imposing fines.
  Sac n.
  1. See 2d Sack.
  2. Biol. A cavity, bag, or receptacle, usually containing fluid, and either closed, or opening into another cavity to the exterior; a sack.
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  sac
       n 1: an enclosed space; "the trapped miners found a pocket of
            air" [syn: pouch, sack, pocket]
       2: a case or sheath especially a pollen sac or moss capsule
          [syn: theca]
       3: a member of the Algonquian people formerly living in
          Wisconsin in the Fox River valley and on the shores of
          Green Bay [syn: Sauk]
       4: a structure resembling a bag in an animal