Synonyms for Invisible:

adj.

•all (adjective)
unseeable.
•invisible (adjective)
imperceptible, Obscured, camouflaged, latent, unobservable, covert, indiscernible, concealed, hidden, unapparent, dark.
•latent (adjective)
unapparent, unexposed, covert, veiled, hidden, camouflaged, unrevealed, clandestine, concealed, buried, unobservable, latent.
•unnoticeable (adjective)
unnoticeable.

a. / adv.

•out of sight (adjective, adverb)
out of sight.

n.

uncertain, anonymous, private, personal, strange, vague, mysterious, unknown, secret. faint, ill-defined, feeble, inappreciable, fuzzy, imponderable, subtle, blurred, knowledge, insensible. •invisible (noun)
hidden, concealed, unseen, infrared, nonvisual, camouflaged, out of sight, lightless, unnoticeable, ultraviolet, undetectable, occult, inconspicuous, obscure, unseeable.

Other synonyms:

blurred, indistinct, inappreciable, ill-defined. impalpable, intangible, insensible, imponderable. faint, vague, subtle, feeble. fuzzy. •indistinct
indistinguishable.
•preternatural
supernatural.

Usage examples for invisible

1. A keen- eyed fellow is this young soldier and a splendid shot, and the Indians who succeed in crossing that next ridge a mile farther south and approaching them unobserved will have to wear the cap of the " Invisible Prince." – 'Laramie;' or, The Queen of Bedlam. by Charles King

2. But that is the first time in my life, and, up to now, the last, that I ever sang to a totally invisible audience! – A Minstrel In France by Harry Lauder

3. I think the tie is like the mystery of the electric wave that passes under the sea, unseen yet acknowledged of all, active though invisible – Nooks and Corners of the New England Coast by Samuel Adams Drake