1. (n.) A point in which the rays of light meet, after being reflected or refracted, and at which the image is formed; as, the focus of a lens or mirror.

2. (n.) A point so related to a conic section and certain straight line called the directrix that the ratio of the distance between any point of the curve and the focus to the distance of the same point from the directrix is constant.

3. (n.) A central point; a point of concentration.

4. (v. t.) To bring to a focus; to focalize; as, to focus a camera.

adductor approach asymptote attractant attrahent axiom blurred blurry bottleneck bring into focus center center of attraction center of consciousness center of interest clear collision course concenter concentralization concentralize concentrate concentration concourse concurrence confluence conflux congress converge convergence converging core crossing cynosure distinct elixir essence essential fix fixate flower focal point focalization focalize focus of attention fundamental funnel fuzzy gist gravamen heart hub hypostasis in focus indistinct inner essence kernel lodestar lure magnet marrow meat meet meeting mutual approach narrowing gap nave nerve nub nucleus nuts and bolts out of focus pinpoint pith point of convergence polestar postulate prime focus principle put quid quiddity quintessence radius rivet sap soul spirit spokes spotlight stuff substance tangent target the nitty-gritty unclear woolly zero in