The Collaborative International Dictionary of English v.0.48:

Vocalist \Vo"cal*ist\, n. [Cf. F. vocaliste.]
   A singer, or vocal musician, as opposed to an
   instrumentalist.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vocalist
    n 1: a person who sings [syn: singer, vocalist, vocalizer,
         vocaliser]