The Collaborative International Dictionary of English v.0.48:

Unaltered \Unaltered\
   See altered.

WordNet (r) 3.0 (2006):

unaltered
    adj 1: remaining in an original state; "persisting unaltered
           through time" [syn: unaltered, unchanged] [ant:
           altered]

Moby Thesaurus II by Grady Ward, 1.0:

62 Moby Thesaurus words for "unaltered":
   abiding, changeless, constant, continuing, durable, enduring, firm,
   fixed, frozen, immobile, immutable, incommutable, inconvertible,
   indefeasible, inert, insusceptible of change, intact,
   intransmutable, invariable, inviolate, irretrievable, irreversible,
   irrevocable, lasting, noble, nonreturnable, nonreversible,
   permanent, perpetual, persistent, quiescent, remaining,
   reverseless, rigid, solid, stable, static, stationary, staying,
   steadfast, sustained, torpid, unalterable, unalterative,
   unchangeable, unchanged, unchanging, unchecked, undeflectable,
   undestroyed, undeviating, unfading, unfailing, unmodifiable,
   unremitting, unrestorable, unreturnable, unshifting, unsusceptible,
   unvariable, unvaried, unvarying