The Collaborative International Dictionary of English v.0.48:

Thirsty \Thirst"y\, a. [Compar. Thirstier; superl.
   Thirstiest.] [AS. ?urstig. See Thirst, n.]
   1. Feeling thirst; having a painful or distressing sensation
      from want of drink; hence, having an eager desire.
      [1913 Webster]

            Give me, I pray thee, a little water to drink, for I
            am thirsty.                           --Judges iv.
                                                  19.
      [1913 Webster]

   2. Deficient in moisture; dry; parched.
      [1913 Webster]

            A dry and thirsty land, where no water is. --Ps.
                                                  lxiii. 1.
      [1913 Webster]

            When in the sultry glebe I faint,
            Or on the thirsty mountain pant.      --Addison.
      [1913 Webster]

WordNet (r) 3.0 (2006):

thirsty
    adj 1: needing moisture; "thirsty fields under a rainless sky"
    2: feeling a need or desire to drink; "after playing hard the
       children were thirsty" [ant: hungry]
    3: (usually followed by `for') extremely desirous; "athirst for
       knowledge"; "hungry for recognition"; "thirsty for
       informaton" [syn: athirst(p), hungry(p), thirsty(p)]
    4: able to take in large quantities of moisture; "thirsty
       towels"

Moby Thesaurus II by Grady Ward, 1.0:

66 Moby Thesaurus words for "thirsty":
   Saharan, absorbent, adsorbent, agog, anhydrous, anxious, ardent,
   arid, assimilative, athirst, avaricious, avid, bibulous, blotting,
   bone-dry, breathless, burning, chemisorptive, chemosorptive,
   consumed with desire, coveting, craving, dehydrated, desert,
   desirous, devoured by desire, digestive, droughty, dry,
   dry as dust, dusty, eager, endosmotic, exosmotic, fervid, greedy,
   hankering, high and dry, hungering, hungry, imbibitory, impatient,
   itching, juiceless, keen, like parchment, mad with lust,
   moistureless, osmotic, parched, prurient, ravenous, resorbent,
   sandy, sapless, sere, soaking, sorbent, spongeous, spongy,
   thirsting, undamped, unwatered, voracious, waterless, yearning