trifocal Hear it!

trifocal definition

☆ tri·fo·cal (trī fō′kəl; also, and for n. usually, trī′fō′kəl)

adjective

adjusted to three different focal lengths

noun

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 in)

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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