1) Central 2) Double vision 3) Dual-purpose bit of eyewear 4) Having two foci 5) Kind of spectacles 6) Lens type 7) Like some eyeglass lenses 8) Like some glasses 9) Like some lenses 10) Split right before your eyes 11) Type of lens 12) Vision corrector 1) Lens 
A lens with two focal lengths, usually for distance/near vision.
• (a.) Having two foci, as some spectacle lenses.
Having two foci. ... (05 Mar 2000) ... 
(bi-fo´-) (bi´fo-kәl) of a lens, having two areas with different refractive powers.
Bi·fo'cal adjective [ Prefix bi-+ focal .] Having two foci, as some spectacle lenses. 
Type: Term Pronunciation: bī-fō′kăl Definitions: 1. Having two foci.
[adj] - (optics) having two foci
bifocal 1. Having two focal lengths. 2. Having one section that corrects for distant vision and another that corrects for near vision, as an eyeglass lens. 3. Embodying two distinct and often conflicting goals, interests, or courses of action.
a lens that corrects both near and distant vision by having two parts with different focusing strengths 
adjective having two foci; `bifocal eyeglasses`
having two foci. · (of an eyeglass or contact lens) having two portions, one for near and one for far vision.