Wordnet 3.0
ADJECTIVE (1)
1.
incapable of being modified in form or character or strength (especially by making less extreme);
- Example: "these variations from custom are illogical, incomprehensible, and unmodifiable"
The Collaborative International Dictionary of English v.0.48:
Unmodifiable \Unmodifiable\
See modifiable.
WordNet (r) 3.0 (2006):
unmodifiable
adj 1: incapable of being modified in form or character or
strength (especially by making less extreme); "these
variations from custom are illogical, incomprehensible,
and unmodifiable" [ant: modifiable]