Source : Webster's Revised Unabridged Dictionary (1913)

Hypnocyst \Hyp"no*cyst\, n. [Gr. ? sleep + E. cyst.] (Biol.)
   A cyst in which some unicellular organisms temporarily
   inclose themselves, from which they emerge unchanged, after a
   period of drought or deficiency of food. In some instances, a
   process of spore formation seems to occur within such cysts.