The Collaborative International Dictionary of English v.0.48:

Prima donna \Pri"ma don"na\; pl. E. Prima donnas, It. Prime
   Donne . [It., fr. primo, prima, the first + donna lady,
   mistress. See {Prime, a., and Donna.]
   The first or chief female singer in an opera.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prima donna
    n 1: a vain and temperamental person
    2: a distinguished female operatic singer; a female operatic
       star [syn: prima donna, diva]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "prima donna":
   Heldentenor, Meistersinger, alto, aria singer, baritenor, baritone,
   bass, basso, basso buffo, basso cantante, basso profundo,
   blues singer, canary, cantatrice, cantor, caroler, chanter,
   chantress, chief, coloratura soprano, comic bass, contralto,
   countertenor, crooner, danseur noble, deep bass, diva,
   dramatic soprano, electronics king, feature attraction,
   first tragedian, headliner, heavy lead, hero, heroic tenor,
   heroine, honcho, hymner, improvisator, jeune premier, king, lead,
   lead singer, leading lady, leading light, leading man,
   lieder singer, luminary, master spirit, melodist, mezzo-soprano,
   opera singer, paramount, prima ballerina, principal, protagonist,
   psalm singer, rock-and-roll singer, singer, singstress, songbird,
   songster, songstress, soprano, star, superstar, tenor, top dog,
   torch singer, vocalist, vocalizer, voice, warbler, yodeler