[cis.tern] n [ME, fr. OF cisterne, fr. L cisterna, fr. cista box, chest--more at chest] (13c) 1: an artificial reservoir (as an underground tank) for storing liquids and esp. water (as rainwater)
2: a large usu. silver vessel formerly used (as in cooling wine) at the dining table
3: a fluid-containing sac or cavity in an organism