Invisible.

Invisible; not obvious.

Unseen, invisible. Obsolete.

That cannot be seen; that by its nature is not an object of sight.

Imperceptible.

Invisible.

(un-, prefix1 affix 1.)

(un-, prefix1 affix 1b.)

Invisible.

Imperceptible.

Invisible.

Incapable by its nature of being perceived by the mind or senses; invisible. In early use esp.: incapable of being comprehended (cf. perceive, v. 5).

Kept from knowledge or observation; hidden, concealed. Hidden from sight; not discernible or visible; unseen (chiefly poetic). Also secret dovetail…

Invisible, unseen, dark; impenetrable by vision.

= undiscernible, adj. (Common in 17th cent.)

? Unseen, invisible.

That cannot be perceived by the eye; invisible. Now archaic and rare (chiefly literary or poetic in later use).

Incapable of being perceived; = imperceptible, adj. (in either sense).

(un-, prefix1 affix 1b.)

That cannot be seen; invisible. Obsolete.

= indiscernible, adj.

Invisible.

That cannot be seen or discerned; invisible.

= unperceptible, adj.

poetic and literary. That cannot be perceived; imperceptible. Obsolete.