The Collaborative International Dictionary of English v.0.48:

Crosier \Cro"sier\ (kr?"zh?r), n. [OE. rocer, croser, croyser,
   fr. croce crosier, OF. croce, croche, F. crosse, fr. LL.
   crocea, crocia, from the same German or Celtic sourse as F.
   croc hook; akin to E. crook.]
   The pastoral staff of a bishop (also of an archbishop, being
   the symbol of his office as a shepherd of the flock of God.
   [1913 Webster]

   Note: The true shape of the crosier was with a hooked or
         curved top; the archbishop's staff alone bore a cross
         instead of a crook, and was of exceptional, not of
         regular form. --Skeat.
         [1913 Webster]

WordNet (r) 3.0 (2006):

crosier
    n 1: a staff surmounted by a crook or cross carried by bishops
         as a symbol of pastoral office [syn: crosier, crozier]