a central point, as of attraction, attention, or activity: The need to prevent a nuclear war became the focus of all diplomatic efforts.
2.
Physics. a point at which rays of light, heat, or other radiation, meet after being refracted or reflected.
3.
Optics.
a.
the focal point of a lens.
b.
the focal length of a lens.
c.
the clear and sharply defined condition of an image.
d.
the position of a viewed object or the adjustment of an optical device necessary to produce a clear image: in focus; out of focus.
4.
Geometry. (of a conic section) a point having the property that the distances from any point on a curve to it and to a fixed line have a constant ratio for all points on the curve.
5.
Geology. the point of origin of an earthquake.
6.
Pathology. the primary center from which a disease develops or in which it localizes.
–verb (used with object)
7.
to bring to a focus or into focus: to focus the lens of a camera.
A point at which rays of light or other radiation converge or from which they appear to diverge, as after refraction or reflection in an optical system: the focus of a lens. Also called focal point.
The distinctness or clarity of an image rendered by an optical system.
The state of maximum distinctness or clarity of such an image: in focus; out of focus.
An apparatus used to adjust the focal length of an optical system in order to make an image distinct or clear: a camera with automatic focus.
The distinctness or clarity of an image rendered by an optical system.
The state of maximum distinctness or clarity of such an image: in focus; out of focus.
An apparatus used to adjust the focal length of an optical system in order to make an image distinct or clear: a camera with automatic focus.
A center of interest or activity. See Synonyms at center.
Close or narrow attention; concentration: "He was forever taken aback by [New York's] pervasive atmosphere of purposefulness—the tight focus of its drivers, the brisk intensity of its pedestrians"(Anne Tyler).
A condition in which something can be clearly apprehended or perceived: couldn't get the problem into focus.
Pathology The region of a localized bodily infection or disease.
Geology The point of origin of an earthquake.
Mathematics A fixed point whose relationship with a directrix determines a conic section.
v.
fo·cused or fo·cussed, fo·cus·ing or fo·cus·sing, fo·cus·es or fo·cus·ses
v.
tr.
To cause (light rays, for example) to converge on or toward a central point; concentrate.
To render (an object or image) in clear outline or sharp detail by adjustment of one's vision or an optical device; bring into focus.
To adjust (a lens, for example) to produce a clear image.
To direct toward a particular point or purpose: focused all their attention on finding a solution to the problem.
v.
intr.
To converge on or toward a central point of focus; be focused.
To adjust one's vision or an optical device so as to render a clear, distinct image.
To concentrate attention or energy: a campaign that focused on economic issues.
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