Entry 4 senses · 3 variants Webster, 1913 Sac /(sa̤k)/ · IPA /sæk/ n. n. n. 01 n. See Sacs. 1. See Sacs.(Ethnol.) See: Sacs 02 n. The privilege formerly enjoyed by the lord of a manor, of holding courts, trying causes, and imposing fines. 1. The privilege formerly enjoyed by the lord of a manor, of holding courts, trying causes, and imposing fines.(O.Eng. Law) 03 n. See 2d Sack. 1. See 2d Sack. See: Sack 2. A cavity, bag, or receptacle, usually containing fluid, and either closed, or opening into another cavity to the exterior; a sack.(Biol.)