n. a transparent optical device used to converge or diverge transmitted light and to form images
n. genus of small erect or climbing herbs with pinnate leaves and small inconspicuous white flowers and small flattened pods: lentils
n. (metaphor) a channel through which something can be seen or understood
n. biconvex transparent body situated behind the iris in the eye; its role (along with the cornea) is to focuses light on the retina