The Collaborative International Dictionary of English v.0.48:

Fossilize \Fos"sil*ize\, v. t. [imp. & p. p. Fossilized; p.
   pr. & vb. n. Fossilizing.] [Cf. F. fossiliser.]
   1. To convert into a fossil; to petrify; as, to fossilize
      bones or wood.
      [1913 Webster]

   2. To cause to become antiquated, rigid, or fixed, as by
      fossilization; to mummify; to deaden.
      [1913 Webster]

            Ten layers of birthdays on a woman's head
            Are apt to fossilize her girlish mirth. --Mrs.
                                                  Browning.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Fossilized \Fos"sil*ized\, a.
   Converted into a fossil; antiquated; firmly fixed in views or
   opinions.
   [1913 Webster]

         A fossilized sample of confused provincialism. --Earle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fossilized
    adj 1: set in a rigidly conventional pattern of behavior,
           habits, or beliefs; "obsolete fossilized ways"; "an
           ossified bureaucratic system" [syn: fossilized,
           fossilised, ossified]

Moby Thesaurus II by Grady Ward, 1.0:

71 Moby Thesaurus words for "fossilized":
   Gothic, Victorian, anile, antediluvian, antiquated, antique,
   archaic, backed, calcified, callous, calloused, case-hardened,
   classical, crabbed, crusted, crusty, crystallized, debilitated,
   decrepit, doddered, doddering, doddery, feeble, fossil, gerontal,
   gerontic, granulated, grown old, hardened, hornified, incrusted,
   indurate, indurated, infirm, lapidified, medieval, mid-Victorian,
   mossbacked, moth-eaten, mummylike, of other times, old-world,
   ossified, palsied, papery-skinned, petrified, ravaged with age,
   reinforced, rickety, rigidified, run to seed, rusty, sclerotic,
   senile, set, shaky, shriveled, solidified, steeled, stiffened,
   strengthened, stricken in years, superannuated, timeworn,
   tottering, tottery, toughened, vitrified, weak, withered,
   wizened