The Collaborative International Dictionary of English v.0.48:

Overeager \O`ver*ea"ger\, a.
   Too eager; too impatient. -- O`ver*ea"ger*ly, adv. --
   O"ver*ea"ger*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overeager
    adj 1: excessively eager; "overeager in his pursuit of the girl"

Moby Thesaurus II by Grady Ward, 1.0:

39 Moby Thesaurus words for "overeager":
   accident-prone, at fever pitch, breakneck, careless, delirious,
   desperate, devil-may-care, fanatical, febrile, feverish, frantic,
   frenetic, frenzied, furious, harum-scarum, hasty, headlong, hectic,
   hotheaded, hurried, hysteric, impetuous, infatuated, insane, mad,
   overanxious, overdesirous, overenthusiastic, overzealous,
   perfervid, precipitant, precipitate, precipitous, reckless,
   slap-bang, slapdash, ultrazealous, wanton, wild