The Collaborative International Dictionary of English v.0.48:

Avid \Av"id\, a. [L. avidus, fr. av?re to long: cf. F. avide.
   See Avarice.]
   Longing eagerly for; eager; greedy. "Avid of gold, yet
   greedier of renown." --Southey.
   [1913 Webster]

WordNet (r) 3.0 (2006):

avid
    adj 1: (often followed by `for') ardently or excessively
           desirous; "avid for adventure"; "an avid ambition to
           succeed"; "fierce devouring affection"; "the esurient
           eyes of an avid curiosity"; "greedy for fame" [syn:
           avid, devouring(a), esurient, greedy]
    2: marked by active interest and enthusiasm; "an avid sports
       fan" [syn: avid, zealous]

Moby Thesaurus II by Grady Ward, 1.0:

76 Moby Thesaurus words for "avid":
   a hog for, acquisitive, agog, alacritous, all agog, all-devouring,
   animated, anxious, ardent, athirst, avaricious, bottomless,
   breathless, bursting to, coveting, covetous, craving, desirous,
   devouring, eager, esurient, forward, full of life, gluttonous,
   gobbling, grabby, grasping, greedy, hoggish, impatient,
   importunate, insatiable, insatiate, insistent, keen, limitless,
   lively, mercenary, miserly, money-hungry, money-mad, omnivorous,
   overgreedy, panting, piggish, pressing, prompt, quenchless, quick,
   rapacious, raring to, ravening, ravenous, ready, ready and willing,
   slakeless, sordid, spirited, swinish, thirsty, unappeasable,
   unappeased, unquenchable, unsated, unsatisfied, unslakeable,
   unslaked, urgent, venal, vital, vivacious, vivid, voracious,
   wanting, wishful, zestful