from The American Heritage® Dictionary of the English Language, 4th Edition
- adj. Having three focal lengths.
- adj. 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.
- n. A lens having three focal lengths.
- n. Eyeglasses having trifocal lenses.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Of or pertaining to corrective lenses that have three different powers per eye.
Sorry, no etymologies found.