|(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.|
|(Opt.)||See under Lens.|
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.