The Collaborative International Dictionary of English v.0.48:

Precative \Prec"a*tive\, Precatory \Prec"a*to*ry\, a. [L.
   precativus, precatorius, fr. precari to pray. See
   Precarious.]
   Suppliant; beseeching. --Bp. Hopkins.
   [1913 Webster]

   Precatory words (Law), words of recommendation, request,
      entreaty, wish, or expectation, employed in wills, as
      distinguished from express directions; -- in some cases
      creating a trust. --Jarman.
      [1913 Webster]

WordNet (r) 3.0 (2006):

precative
    adj 1: expressing entreaty or supplication; "precatory
           overtures" [syn: precatory, precative]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "precative":
   adjuratory, adorant, adoring, appealing, begging, beseeching,
   cadging, devotional, devout, entreating, imploring, in the dust,
   mendicant, mooching, on bended knee, petitionary, pleading,
   prayerful, precatory, prostrate before, reverent, reverential,
   scrounging, solemn, suppliant, supplicant, supplicating,
   supplicatory, venerational, venerative, worshipful, worshiping