Focus

Definition of Focus

Fo´cus   Pronunciation: fō´kŭs
n.1.(Opt.) 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.(Geom.) 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.A central point; a point of concentration.
Aplanatic focus
(Opt.) See under Aplanatic.
Conjugate focus
(Opt.) the focus for rays which have a sensible divergence, as from a near object; - so called because the positions of the object and its image are interchangeable.
Focus tube
(Phys.) a vacuum tube for Rœntgen rays in which the cathode rays are focused upon the anticathode, for intensifying the effect.
Principal focus
(Opt.) the focus for parallel rays.
v. t.1.To bring to a focus; to focalize; as, to focus a camera.
[imp. & p. p. Focused ; p. pr. & vb. n. Focusing.]

Related Words

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
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fo'c'sle
Foal
Foal teeth
Foalfoot
Foam
Foam cock
foaming
foamingly
foamless
foamy
Fob
Fob chain
Focal
Focal distance of a telescope
Focal distance, or length, of a lens or mirror
Focalization
Focalize
Focillate
Focillation
Focimeter
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Focus tube
focused
focusing
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Fodder
Fodderer
Fodient
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Foe
Foehn
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foetus
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