%foc%

n. [ Pref. bi-+ focal. ] a bifocal lens. [ PJC ]

n. pl. [ Pref. bi-+ focal. ] eyeglasses whose lenses have two foci, allowing the wearer to see both far and nearby objects clearly. The lenses are partitioned horizontally, the upper and lower parts having different focal lengths. [ PJC ]

a. (Math.) Having the same foci; as, confocal quadrics. [ 1913 Webster ]

a. [ Cf. F. focal. See Focus. ] Belonging to, or concerning, a focus; as, a focal point. [ 1913 Webster ]

Focal distance, or length, of a lens or mirror (Opt.), the distance of the focus from the surface of the lens or mirror, or more exactly, in the case of a lens, from its optical center. --
Focal distance of a telescope, the distance of the image of an object from the object glass. [ 1913 Webster ]

n. The act of focalizing or bringing to a focus, or the state of being focalized. [ 1913 Webster ]

v. t. [ imp. & p. p. Focalized p. pr. & vb. n. Focalizing ] To bring to a focus; to focus; to concentrate. [ 1913 Webster ]

Light is focalized in the eye, sound in the ear. De Quincey. [ 1913 Webster ]

v. t. [ L. focilatus, p. p. of focillare. ] To nourish. [ Obs. ] Blount. [ 1913 Webster ]

n. Comfort; support. [ Obs. ] [ 1913 Webster ]

n. [ Focus + -meter. ] (Photog.) An assisting instrument for focusing an object in or before a camera. Knight. [ 1913 Webster ]

n.; pl. E. Focuses L. Foci [ L. focus hearth, fireplace; perh. akin to E. bake. Cf. Curfew, Fuel, Fusil the firearm. ] 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. [ 1913 Webster ]

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. [ 1913 Webster ]

☞ Thus, in the ellipse FGHKLM, A is the focus and CD the directrix, when the ratios FA:FE, GA:GD, MA:MC, etc., are all equal. So in the hyperbola, A is the focus and CD the directrix when the ratio HA:HK is constant for all points of the curve; and in the parabola, A is the focus and CD the directrix when the ratio BA:BC is constant. In the ellipse this ratio is less than unity, in the parabola equal to unity, and in the hyperbola greater than unity. The ellipse and hyperbola have each two foci, and two corresponding directrixes, and the parabola has one focus and one directrix. In the ellipse the sum of the two lines from any point of the curve to the two foci is constant; that is: AG + GB = AH + HB; and in the hyperbola the difference of the corresponding lines is constant. The diameter which passes through the foci of the ellipse is the major axis. The diameter which being produced passes through the foci of the hyperbola is the transverse axis. The middle point of the major or the transverse axis is the center of the curve. Certain other curves, as the lemniscate and the Cartesian ovals, have points called foci, possessing properties similar to those of the foci of conic sections. In an ellipse, rays of light coming from one focus, and reflected from the curve, proceed in lines directed toward the other; in an hyperbola, in lines directed from the other; in a parabola, rays from the focus, after reflection at the curve, proceed in lines parallel to the axis. Thus rays from A in the ellipse are reflected to B; rays from A in the hyperbola are reflected toward L and M away from B. [ 1913 Webster ]

3. A central point; a point of concentration. [ 1913 Webster ]

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, or
Solar focus (Opt.), the focus for parallel rays. [ 1913 Webster ]

v. t. [ imp. & p. p. Focused p. pr. & vb. n. Focusing. ] To bring to a focus; to focalize; as, to focus a camera. R. Hunt. [ 1913 Webster ]

adj. [ Also spelled focussed. ] 1. being in focus or brought into focus; clearly delineated; -- of an image. Opposite of unfocused. [ WordNet 1.5 ]

2. converging on a point; -- of light rays; as, focused light rays can set something afire. [ WordNet 1.5 ]

3. concentrated on or clustered around a central point or purpose.
Syn. -- centered, centred, centralized. [ WordNet 1.5 ]

adj. 1. same as focused (in all senses).
Syn. -- focused. [ WordNet 1.5 ]

n. 1. the concentration of attention or energy on something.
Syn. -- focus, focussing. [ WordNet 1.5 ]

2. the act of bringing into focus.
Syn. -- focalization, focalisation. [ WordNet 1.5 ]

n. [ Of uncertain etymol.; perh. for L. loco foci instead of fire; or, according to Bartlett, it was called so from a self-lighting cigar, with a match composition at the end, invented in 1834 by John Marck of New York, and called by him locofoco cigar, in imitation of the word locomotive, which by the uneducated was supposed to mean, self-moving. ] 1. A friction match. [ U.S. ] [ 1913 Webster ]

2. A nickname formerly given to a member of the Democratic party. [ U.S. ] [ 1913 Webster ]

☞ The name was first applied, in 1834, to a portion of the Democratic party, because, at a meeting in Tammany Hall, New York, in which there was great diversity of sentiment, the chairman left his seat, and the lights were extinguished, for the purpose of dissolving the meeting; when those who were opposed to an adjournment produced locofoco matches, rekindled the lights, continued the meeting, and accomplished their object. [ 1913 Webster ]

a. [ Pari- + focal. ] (Opt.) With the lower focal points all in the same plane; -- said of sets of eyepieces so mounted that they may be interchanged without varying the focus of the instrument (as a microscope or telescope) with which they are used. “the convenience of a microscope with parfocal objective lenses” [ Webster 1913 Suppl. ]

v. t. [ L. refocillatus, p. p. of refocillare; pref. re- re- + focillare to revive by warmth. ] To refresh; to revive. [ Obs. ] Aubrey. [ 1913 Webster ]

n. Restoration of strength by refreshment. [ Obs. ] Middleton. [ 1913 Webster ]

v. i. To become choked, stifled, or smothered. “A swelling discontent is apt to suffocate and strangle without passage.” collier. [ 1913 Webster ]

a. [ L. suffocatus, p. p. of suffocare to choke; sub under + fauces the throat. Cf. Faucal. ] Suffocated; choked. Shak. [ 1913 Webster ]

v. t. [ imp. & p. p. Suffocated p. pr. & vb. n. Suffocating. ] 1. To choke or kill by stopping respiration; to stifle; to smother. [ 1913 Webster ]

Let not hemp his windpipe suffocate. Shak. [ 1913 Webster ]

2. To destroy; to extinguish; as, to suffocate fire. [ 1913 Webster ]

a. & n. from Suffocate, v. -- Suf"fo*ca`ting*ly, adv. [1913 Webster]

n. [ L. suffocatio: cf. F. suffocation. ] The act of suffocating, or the state of being suffocated; death caused by smothering or choking. [ 1913 Webster ]

☞ The term suffocation is sometimes employed synonymously with asphyxia. In the strict medico-legal sense it signifies asphyxia induced by obstruction of the respiration otherwise than by direct pressure on the neck (hanging, strangulation) or submersion (drowning). Quain. [ 1913 Webster ]