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.
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.
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.
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.