trifocals
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English[edit]
Etymology[edit]
From tri- + focal (see focus). Coined by John Isaac Hawkins, their inventor, in 1826.
Noun[edit]
trifocals pl (plural only)
- (optics) Spectacles with corrective lenses that have three different powers per eye.
Related terms[edit]
Translations[edit]
type of spectacles
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