calyx (n.)

"outer part of the perianth of a flower," 1680s, from Latin calyx, from Greek kalyx "seed pod, husk, outer covering" (of a fruit, flower bud, etc.), from stem of kalyptein "to cover, conceal," from PIE root *kel- (1) "to cover, conceal, save." The Latin plural is calyces. Some sources connect the word rather with Greek kylix "drinking cup" (see chalice).