n. 1 a piece of a transparent substance with one or (usu.) both sides curved for concentrating or dispersing light-rays esp. in optical instruments. 2 a combination of lenses used in photography. 3 Anat. = crystalline lens. 4 Physics a device for focusing or otherwise modifying the direction of movement of light, sound, electrons, etc. lensed adj. lensless adj.
[ L lens lentis lentil (from the similarity of shape) ]