Synonyms for Unseen (same or very similar meaning)
WordNet sense 1 (a belief that there is a realm controlled by a divine spirit):
spiritual world
WordNet sense 2 (impossible or nearly impossible to see; imperceptible by the eye):
invisible, unseeable
WordNet sense 3 (not observed):
unobserved
WordNet sense 4 (not perceived or discerned):
undetected
From the ODE community, based on WordNet
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