the GNU version of the Collaborative International Dictionary of English
adj. Not perceivable by the eye; invisible; unseen.
The Century Dictionary and Cyclopedia
Not capable of being viewed or seen; not perceived by the eye; invisible.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. not having or expressing opinions or views
Word Usage
"This previous tenant reports hearing strange voices in this room and waking up several times at 3 in morning and either seeing a shadowy figure at the foot of the bed or faces staring in the viewless window."