What does "trifocals" mean?

Spectacles with corrective lenses that have three different powers per eye.

What is a synonym for "trifocals"?

Common synonyms include: bifocals, contact lens, eyeglass, eyeglasses, glass, glasses.

noun

noun ·Rare ·Advanced level

Noun

1
Spectacles with corrective lenses that have three different powers per eye. plural, plural-only

From tri- + focal (see focus). Coined by John Isaac Hawkins, their inventor, in 1826.