trifocal — ☆ trifocal [trī fō′kəl; ] also, and for n. usually [, trī′fō΄kəl ] adj. adjusted to three different focal lengths n. a lens like a bifocal but with an additional narrow area ground to adjust the intermediate focus for objects at c. 76 cm ( c. 30… … English World dictionary
trifocal — I. adjective Date: 1826 having three focal lengths II. noun Date: 1899 1. plural eyeglasses with trifocal lenses 2. a trifocal glass or lens … New Collegiate Dictionary
Trifocal — Trifocals are eyeglasses where the lenses have 3 regions to correct for distance, intermediate (arm s length), and near vision. They are mostly used by people with advanced presbyopia who have been prescribed 2 diopters or more of reading… … Wikipedia
trifocal — /truy foh keuhl, truy foh /, adj. 1. Optics. having three foci. 2. (of an eyeglass lens) having three portions, one for near, one for intermediate, and one for far vision. n. 3. trifocals, eyeglasses with trifocal lenses. [1945 50; TRI + FOCAL] * … Universalium
trifocal — adjective (of a pair of glasses) having lenses with three parts with different focal lengths. noun (trifocals) a pair of trifocal glasses … English new terms dictionary
trifocal — tri•fo•cal [[t]traɪˈfoʊ kəl, ˈtraɪˌfoʊ [/t]] adj. 1) opt (of a lens) having three foci 2) (of an eyeglass lens) having three portions, one for near, one for intermediate, and one for far vision 3) trifocals, eyeglasses with trifocal lenses •… … From formal English to slang
trifocal — adj. & n. adj. having three focuses, esp. of a lens with different focal lengths. n. (in pl.) trifocal spectacles … Useful english dictionary
Trifocal tensor — In computer vision, the trifocal tensor can be considered as the generalization of the fundamental matrix in three views. It is a tensor thatincorporates all projective geometric relationships between three views andis independent of the scene… … Wikipedia
trifocal glasses — glasses with trifocal lenses … Medical dictionary
trifocal lens — a lens that has three segments with different refractive powers, ordinarily with the upper for distant, the middle for intermediate, and the lower for near vision; used in trifocal glasses … Medical dictionary
