Definition of: lens

(lenz) noun
1. A piece of glass or other transparent substance, bounded by two surfaces, of different curvature, generally spherical, or by one spherical or curved, and one plane surface, by which rays of light may be made to converge or to diverge. ♦ Collateral adjective: lenticular.
2. Any device for concentrating or dispersing radiation by refraction.
3. A biconvex transparent body situated behind the iris of the eye. See illustration under EYE.
—crown lens The convex portion in an achromatic lens. [<L lens, lentis a lentil; so called from the similarity in form]
LENS
a. Convexo–convex.
b. Plano–convex.
c. Convexo–concave.
d. Concavo–concave.
e. Plano–concave.
ƒ. Concavo–convex.