The apprehension of fact or truth with the mind; clear and certain perception of fact or truth; the state or condition of knowing fact or truth.

Keen or clear perception; insight. In early use also: †the ability to see all things, infinite vision (obsolete). Cf. perspicacity, n.

Distinctness of vision, sound, expression, comprehension, etc.

Clearness of understanding or insight; great mental penetration; discernment.

The fact of penetrating with the eyes of the understanding into the inner character or hidden nature of things; a glimpse or view beneath the…

Close inspection; insight, perspicuity. Obsolete.

Refinement (of thought or argument); perspicacity (of intellect). Cf. subtlety, n. 5 subtlety, n. 6b. Now rare.

= perspicacity, n.

Clearness: in various current uses; e.g. of colour, sky, atmosphere, sight, intellect, judgement, conscience, style.

Mental penetration; insight; = perspicacity, n. 1.

= perspicacity, n.

The quality of being percipient; the action, condition, or faculty of perception; recognition; insight.

the state of being far-sighted.

Keenness of mental perception, clearness of insight; insight into things beyond the range of ordinary perception.

Designating very acute discernment, or an apparent ability to see beyond an outward form or through opaque material. Esp. in X-ray eyes, X-ray scr…