trifocal Hear it!

trifocal definition

tri·fo·cal (trī fōkəl; also, and for n. usually, trīfō′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.

Comments
Improve this definition.
Do you have more to add? Share your linguistic knowledge or observation.
/Register to save your comments.