Unperceivable
The Century Dictionary and Cyclopedia
Incapable of being perceived; not perceptible.
Wiktionary, Creative Commons Attribution/Share-Alike License
adjective.
Not
perceivable
;
imperceptible
.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adjective.
impossible or difficult to perceive by the mind or senses