The Collaborative International Dictionary of English v.0.48:

Optative \Op"ta*tive\, a. [L. optativus: cf. F. optatif.]
   Expressing desire or wish. --Fuller.
   [1913 Webster]

   Optative mood (Gram.), that mood or form of a verb, as in
      Greek, Sanskrit, etc., in which a wish or desire is
      expressed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

optative mood
    n 1: a mood (as in Greek or Sanskrit) that expresses a wish or
         hope; expressed in English by modal verbs [syn: optative
         mood, optative]