The Collaborative International Dictionary of English v.0.48:

Lychnis \Lych"nis\, n. [L., a kind of red flower, Gr. lychni`s;
   cf. ly`chnos a lamp.] (Bot.)
   A genus of Old World plants belonging to the Pink family
   (Caryophyllace[ae]). Most of the species have brilliantly
   colored flowers and cottony leaves, which may have anciently
   served as wicks for lamps. The botanical name is in common
   use for the garden species. The corn cockle (Lychnis
   Githago) is a common weed in wheat fields.
   [1913 Webster]

WordNet (r) 3.0 (2006):

lychnis
    n 1: mostly perennial herbs with sticky stems that catch
         insects; widespread in north temperate zone [syn:
         lychnis, catchfly]