The Collaborative International Dictionary of English v.0.48:

Ing'enue \In`g['e]`nue"\ ([a^]N`zh[asl]`n[.u]"), n.; pl.
   -nues. [F., fem. of ing['e]nu ingenious.]
   An ingenuous or na["i]ve girl or young woman, or an actress
   representing such a person.
   [Webster 1913 Suppl.]

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "ingenue":
   Roscius, actor, actress, antagonist, antihero, babe, bad guy,
   barnstormer, bit, bit part, cast, character, character actor,
   character man, character woman, child, child actor,
   child of nature, cue, diseur, diseuse, dove, dramatizer, dupe,
   fat part, feeder, foil, heavy, hero, heroine, hick, histrio,
   histrion, infant, innocent, juvenile, lamb, lead, lead role,
   leading lady, leading man, leading woman, lines, lout,
   matinee idol, mere child, mime, mimer, mimic, monologist, mummer,
   noble savage, oaf, pantomime, pantomimist, part, person, personage,
   piece, playactor, player, protagonist, protean actor, reciter,
   role, rube, side, simple soul, soubrette, stage performer,
   stage player, stooge, straight man, straight part, stroller,
   strolling player, supporting character, supporting role,
   theatrical, thespian, title role, trouper, unsophisticate,
   utility man, villain, walk-on, walking part, yokel