The Collaborative International Dictionary of English v.0.48:

Greenfinch \Green"finch`\, n. (Zool.)
   1. A European finch (Ligurinus chloris); -- called also
      green bird, green linnet, green grosbeak, green
      olf, greeny, and peasweep.
      [1913 Webster]

   2. The Texas sparrow (Embernagra rufivirgata), in which the
      general color is olive green, with four rufous stripes on
      the head.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "greeny":
   apprentice, babe, baby, beginner, boob, catechumen, chump, cinch,
   credulous person, cull, dabbler, deb, debutant, dilettante, dunce,
   dupe, easy mark, easy pickings, entrant, fall guy, fish, fledgling,
   fool, freshman, gobe-mouches, greener, greenhorn, gudgeon, gull,
   ignoramus, illiterate, illiterati, infant, innocent, know-nothing,
   leadpipe cinch, learner, lowbrow, middlebrow, monkey, neophyte,
   nestling, newcomer, no scholar, novice, novitiate, patsy, pigeon,
   plaything, prize sap, probationer, puddinghead, pushover,
   raw recruit, recruit, rookie, sap, saphead, schlemiel,
   sitting duck, stooge, sucker, tenderfoot, toy, trainee,
   trusting soul, tyro, unintelligentsia, victim