athirst

1. Strongly desirous; eager: athirst for freedom.
2. Archaic. Thirsty.

adjective

1. Intensely desirous or interested: agog, ardent, avid, bursting, eager, impatient, keen, solicitous, thirsting, thirsty. Informal raring. Idioms: champing at the bit, ready and willing. See concern/unconcern.
2. Needing or desiring drink: dry, parched, thirsty. See dry/wet.

The adjective has one meaning:

Meaning #1: (usually followed by `for') extremely desirous
  Synonyms: hungry, thirsty