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1. Having three focal lengths.
2. Having one section that corrects for distant vision, a second section that corrects for medium vision, and a third that corrects for near vision, as an eyeglass lens.
1. A lens having three focal lengths.
2. trifocals Eyeglasses having trifocal lenses.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
1. (Mathematics) having three focuses
2. (General Physics) having three focal lengths
(Medicine) (plural) glasses with trifocal lenses
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
tri•fo•cal(traɪˈfoʊ kəl, ˈtraɪˌfoʊ-)
1. (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.n.
3. trifocals, eyeglasses with trifocal lenses.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
___ lenses → lentes ___ -es.
English-Spanish Medical Dictionary © Farlex 2012
English-Spanish/Spanish-English Medical Dictionary Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.