The Collaborative International Dictionary of English v.0.48:

Calypso \Ca*lyp"so\ (k[.a]*l[i^]p"s[-o]), n. [The Latinized
   Greek name of a beautiful nymph.] (Bot.)
   A small and beautiful species of orchid, having a flower
   variegated with purple, pink, and yellow. It grows in cold
   and wet localities in the northern part of the United States.
   The Calypso borealis is the only orchid which reaches
   68[deg] N.
   [1913 Webster]