The Collaborative International Dictionary of English v.0.48:

Unchanging \Unchanging\
   See changing.

WordNet (r) 3.0 (2006):

unchanging
    adj 1: conforming to the same principles or course of action
           over time
    2: showing little if any change; "a static population" [syn:
       static, stable, unchanging]

Moby Thesaurus II by Grady Ward, 1.0:

153 Moby Thesaurus words for "unchanging":
   abiding, accordant, alike, all-knowing, all-powerful, all-seeing,
   all-wise, almighty, automatic, balanced, boundless, ceaseless,
   changeless, chattering, consistent, consonant, constant, continual,
   continuing, continuous, correspondent, creating, creative, durable,
   enduring, equable, equal, eternal, eternally the same, even,
   everlasting, firm, fixed, flat, frozen, glorious, good, hallowed,
   highest, holy, homogeneous, immobile, immortal, immutable,
   incessant, incommutable, inconvertible, indefeasible, inert,
   infinite, insusceptible of change, intact, intransmutable,
   invariable, inviolate, irretrievable, irreversible, irrevocable,
   just, lasting, level, limitless, loving, luminous, machine gun,
   majestic, making, measured, mechanical, merciful, methodic,
   monolithic, noble, nonreturnable, nonreversible, numinous,
   of a piece, omnipotent, omnipresent, omniscient, one, ordered,
   orderly, oscillating, perennial, permanent, perpetual, persistent,
   pulsating, quiescent, radiant, rapid, regular, remaining, repeated,
   reverseless, rigid, robotlike, sacred, shaping, smooth, solid,
   sovereign, stabile, stable, staccato, static, stationary, staying,
   steadfast, steady, stuttering, supreme, sustained, systematic,
   timeless, torpid, ubiquitous, unalterable, unalterative, unaltered,
   unbounded, unbroken, unceasing, unchangeable, unchanged, unchecked,
   undefined, undeflectable, undestroyed, undeviating,
   undifferentiated, undiversified, unfading, unfailing, uniform,
   unintermitted, unintermittent, unintermitting, uninterrupted,
   unlimited, unmodifiable, unremitting, unrestorable, unreturnable,
   unruffled, unshifting, unstopped, unsusceptible, unvariable,
   unvaried, unvarying, vibrating