Wordnet 3.0
ADJECTIVE (1)
1. 
 that may not be returned; 
- Example: "nonreturnable bottles cannot be exchanged for a deposit"- Example: "sale merchandise is nonreturnable"
The Collaborative International Dictionary of English v.0.48:
nonreturnable \nonreturnable\ adj.
   That may not be returned for a refund; -- of purchased goods,
   or containers for purchased items; as, nonreturnable bottles.
   Opposite of returnable.
   [WordNet 1.5]
WordNet (r) 3.0 (2006):
nonreturnable
    adj 1: that may not be returned; "nonreturnable bottles cannot
           be exchanged for a deposit"; "sale merchandise is
           nonreturnable" [ant: returnable]
Moby Thesaurus II by Grady Ward, 1.0:
33 Moby Thesaurus words for "nonreturnable":
   changeless, constant, immutable, incommutable, inconvertible,
   indefeasible, inert, insusceptible of change, intransmutable,
   invariable, irretrievable, irreversible, irrevocable, lasting,
   noble, nonreversible, permanent, reverseless, unalterable,
   unalterative, unaltered, unchangeable, unchanged, unchanging,
   undeflectable, undeviating, unmodifiable, unremitting,
   unrestorable, unreturnable, unsusceptible, unvariable, unvarying