Wordnet 3.0
NOUN (1)
1.
minute aquatic multicellular organisms having a ciliated wheel-like organ for feeding and locomotion;
constituents of freshwater plankton;
The Collaborative International Dictionary of English v.0.48:
Rotifer \Ro"ti*fer\ (?; 277), n. [NL. see Rotifera.] (Zool.)
One of the Rotifera. See Illust. in Appendix.
[1913 Webster]
WordNet (r) 3.0 (2006):
rotifer
n 1: minute aquatic multicellular organisms having a ciliated
wheel-like organ for feeding and locomotion; constituents
of freshwater plankton