bifocal

[bahy-foh-kuh l, bahy-foh-]
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adjective
  1. Chiefly Optics. having two foci.
  2. (of an eyeglass or contact lens) having two portions, one for near and one for far vision.
noun
  1. bifocals, bifocal eyeglasses or contact lenses.

Origin of bifocal

An Americanism dating back to 1885–90; bi-1 + focal
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Related Words for bifocal

glass, spectacles, contact, optic, monocle, meniscus, bifocal, trifocal

Examples from the Web for bifocal

Historical Examples of bifocal


British Dictionary definitions for bifocal

bifocal

adjective
  1. optics having two different focuses
  2. relating to a compound lens permitting near and distant vision
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

Word Origin and History for bifocal
adj.

"having two foci," 1844, from bi- + focal.

Online Etymology Dictionary, © 2010 Douglas Harper

bifocal in Medicine

bifocal

[bī-fōkəl, bīfō′-]
adj.
  1. Having two focal lengths.
  2. Having one section that corrects for distant vision and another that corrects for near vision.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.