Of spherical lenses, there are six varieties, as shown in section in
the figures herewith given: viz., a plano-concave; b double-concave; c
plano-convex; d double- convex; e converging concavo-convex, or
converging meniscus; f diverging concavo-convex, or diverging meniscus.
Crossed lens (Opt.), a double-convex lens with one radius equal to six
times the other. -- Crystalline lens. (Anat.) See Eye. -- Fresnel lens
(Opt.), a compound lens formed by placing around a central convex lens
rings of glass so curved as to have the same focus; used, especially in
lighthouses, for concentrating light in a particular direction; -- so
called from the inventor. -- Multiplying lens or glass (Opt.), a lens
one side of which is plane and the other convex, but made up of a
number of plane faces inclined to one another, each of which presents a
separate image of the object viewed through it, so that the object is,
as it were, multiplied. -- Polyzonal lens. See Polyzonal.
Lent (lnt), imp. & p. p. of Lend.
Lent, n. [OE. lente, lenten, leynte, AS. lengten, lencten, spring,
lent, akin to D. lente, OHG. lenzin, langiz, G. lenz, and perh. fr. AS.
lang long, E. long, because at this season of the year the days
lengthen.] (Eccl.) A fast of forty days, beginning with Ash Wednesday
and continuing till Easter, observed by some Christian churches as
commemorative of the fast of our Savior.
Lent lily (Bot.), the daffodil; -- so named from its blossoming in
spring.
Lent, a. [L. lentus; akin to lenis soft, mild: cf. F. lent. See
Lenient.] 1. Slow; mild; gentle; as, lenter heats. [Obs.] B. Jonson.