The Collaborative International Dictionary of English v.0.48:

Legatary \Leg"a*ta*ry\ (l[e^]g"[.a]*t[asl]*r[y^]), n. [L.
   legatarius, fr. legaturius enjoined by a last will: cf. F.
   l['e]gataire. See Legacy.]
   A legatee. [R.] --Ayliffe.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

LEGATARY. One to whom anything is bequeathed; a legatee. This word is
sometimes though seldom used to designate a legate or nuncio.