trifocal

[ trahy-foh-kuh l, trahy-foh- ]
/ traɪˈfoʊ kəl, ˈtraɪˌfoʊ- /

adjective

Optics. having three foci.
(of an eyeglass lens) having three portions, one for near, one for intermediate, and one for far vision.

noun

trifocals, eyeglasses with trifocal lenses.

Origin of trifocal

First recorded in 1945–50; tri- + focal
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for trifocal

trifocal


adjective (traɪˈfəʊkəl)

having three focuses
having three focal lengths

noun (traɪˈfəʊkəl, ˈtraɪˌfəʊkəl)

(plural) glasses with trifocal lenses
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012