The Collaborative International Dictionary of English v.0.48:

Petrify \Pet"ri*fy\ (p[e^]t"r[i^]*f[imac]), v. t. [imp. & p. p.
   Petrified; p. pr. & vb. n. Petrifying.] [L. petra rock,
   Gr. pe`tra (akin to pe`tros a stone) + -fy: cf. F.
   p['e]trifier. Cf. Parrot, Petrel, Pier.]
   1. To convert, as any animal or vegetable matter, into stone
      or stony substance; as, petrified wood.
      [1913 Webster]

            A river that petrifies any sort of wood or leaves.
                                                  --Kirwan.
      [1913 Webster]

   2. To make callous or obdurate; to transform, as by
      petrifaction; as, to petrify the heart. Young. "Petrifying
      accuracy." --Sir W. Scott.
      [1913 Webster]

            And petrify a genius to a dunce.      --Pope.
      [1913 Webster]

            A hideous fatalism, which ought, logically, to
            petrify your volition.                --G. Eliot.
      [1913 Webster]

   3. To paralyze, especially with fear; to stupefy; as, she was
      petrified by the sight of the bear in her tent.
      [PJC]

            The poor, petrified journeyman, quite unconscious of
            what he was doing.                    --De Quincey.
      [1913 Webster]

WordNet (r) 3.0 (2006):

petrifying
    adj 1: paralyzing with terror

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "petrifying":
   bloodcurdling, hair-raising, hardening, indurative, paralyzing,
   petrifactive, stunning, stupefying, terrifying, terror,
   terror-bearing, terror-breathing, terror-breeding, terror-bringing,
   terror-fraught, terror-giving, terror-inspiring, terror-striking,
   terrorful, terroristic, toughening