From WordNet (r) 3.0 (2006) [wn]:
dancer
n 1: a performer who dances professionally [syn: dancer,
professional dancer, terpsichorean]
2: a person who participates in a social gathering arranged for
dancing (as a ball) [syn: dancer, social dancer]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Dancer \Dan"cer\, n.
One who dances or who practices dancing.
[1913 Webster]
The merry dancers, beams of the northern lights when they
rise and fall alternately without any considerable change
of length. See Aurora borealis, under Aurora.
[1913 Webster]