I. ˈbī-ˌfō-kəl adjective
Etymology: International Scientific Vocabulary
Date: 1888
1. : having two focal lengths
2. : having one part that corrects for near vision and one for distant vision
a bifocal eyeglass lens
II. noun
Date: 1899
1. plural : eyeglasses with bifocal lenses
2. : a bifocal glass or lens