The Collaborative International Dictionary of English v.0.48:

Hieratic \Hi`er*at"ic\, a. [L. hieraticus, Gr. "ieratiko`s; akin
   to "iero`s sacred: cf. F. hi['e]ratique.]
   Consecrated to sacred uses; sacerdotal; pertaining to
   priests.
   [1913 Webster]

   Hieratic character, a mode of ancient Egyptian writing; a
      modified form of hieroglyphics, tending toward a cursive
      hand and formerly supposed to be the sacerdotal character,
      as the demotic was supposed to be that of the people.
      [1913 Webster]

            It was a false notion of the Greeks that of the
            three kinds of writing used by the Egyptians, two --
            for that reason called hieroglyphic and hieratic --
            were employed only for sacred, while the third, the
            demotic, was employed for secular, purposes. No such
            distinction is discoverable on the more ancient
            Egyptian monuments; bur we retain the old names
            founded on misapprehension.           --W. H. Ward
                                                  (Johnson's
                                                  Cyc.).
      [1913 Webster]

WordNet (r) 3.0 (2006):

hieratic
    adj 1: associated with the priesthood or priests; "priestly (or
           sacerdotal) vestments"; "hieratic gestures" [syn:
           priestly, hieratic, hieratical, sacerdotal]
    2: written or belonging to a cursive form of ancient Egyptian
       writing; "hieratic Egyptian script"
    3: adhering to fixed types or methods; highly restrained and
       formal; "the more hieratic sculptures leave the viewer
       curiously unmoved"
    n 1: a cursive form of Egyptian hieroglyphics; used especially
         by the priests [syn: hieratic, hieratic script]