Wordnet 3.0
NOUN (1)
1.
one of the often brightly colored and branching hornlike structures on the back of the nudibranch (and other related mollusks) that serve as gills;
The Collaborative International Dictionary of English v.0.48:
ceras \ceras\ n.
one of the often brightly colored and branching hornlike
structures on the backs of nudibranchs and other related
mollusks that serve as gills.
[WordNet 1.5]
WordNet (r) 3.0 (2006):
ceras
n 1: one of the often brightly colored and branching hornlike
structures on the back of the nudibranch (and other related
mollusks) that serve as gills