The Collaborative International Dictionary of English v.0.48:

Singer \Sin"ger\ (s[i^]n"j[~e]r), n. [From Singe.]
   One who, or that which, singes. Specifically:
   (a) One employed to singe cloth.
   (b) A machine for singeing cloth.
       [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Singer \Sing"er\, n. [From Sing.]
   One who sings; especially, one whose profession is to sing.
   [1913 Webster]

WordNet (r) 3.0 (2006):

singer
    n 1: a person who sings [syn: singer, vocalist, vocalizer,
         vocaliser]
    2: United States inventor of an improved chain-stitch sewing
       machine (1811-1875) [syn: Singer, Isaac M. Singer, Isaac
       Merrit Singer]
    3: United States writer (born in Poland) of Yiddish stories and
       novels (1904-1991) [syn: Singer, Isaac Bashevis Singer]

Moby Thesaurus II by Grady Ward, 1.0:

110 Moby Thesaurus words for "singer":
   Heldentenor, Meistersinger, alto, aria singer, artist, artiste,
   balladeer, baritenor, baritone, bass, basso, basso buffo,
   basso cantante, basso profundo, belly dancer, blues singer,
   burlesque queen, canary, cantatrice, cantor, caroler, chanter,
   chantress, choir member, choirboy, chorine, chorister, chorus boy,
   chorus girl, coloratura soprano, comic bass, conjurer, contralto,
   coryphee, countertenor, crooner, dancer, dancing girl,
   danseur noble, deep bass, diva, dramatic soprano, ecdysiast,
   entertainer, exotic dancer, feature attraction,
   female impersonator, first tragedian, geisha, geisha girl, guisard,
   guiser, headliner, heavy lead, hero, heroic tenor, heroine, hoofer,
   hymner, impersonator, improvisator, jeune premier, lead,
   lead singer, leading lady, leading man, lieder singer, magician,
   melodist, mezzo-soprano, minstrel, mountebank, mummer, musician,
   nautch girl, nightingale, opera singer, peeler, performer,
   prestidigitator, prima ballerina, prima donna, principal,
   protagonist, psalm singer, public entertainer,
   rock-and-roll singer, show girl, singstress, soloist, songbird,
   songster, songstress, soprano, star, stripper, stripteaser,
   stripteuse, superstar, tenor, thrush, torch singer, troubador,
   vaudevillian, vaudevillist, vocalist, vocalizer, voice, warbler,
   yodeler