a. 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.
a. The distinctness or clarity of an image rendered by an optical system.
b. The state of maximum distinctness or clarity of such an image: in focus; out of focus.
c. 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.
3. A center of interest or activity. See Synonyms at center.
4. Close or narrow attention; concentration: He was forever taken aback by [New Yorks] pervasive atmosphere of purposefulnessthe tight focus of its drivers, the brisk intensity of its pedestrians(Anne Tyler).
5. A condition in which something can be clearly apprehended or perceived: couldnt get the problem into focus.
6. Pathology The region of a localized bodily infection or disease.
7. Geology The point of origin of an earthquake.
8. 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
1. To cause (light rays, for example) to converge on or toward a central point; concentrate.
a. To render (an object or image) in clear outline or sharp detail by adjustment of ones vision or an optical device; bring into focus.
b. To adjust (a lens, for example) to produce a clear image.
3. To direct toward a particular point or purpose: focused all their attention on finding a solution to the problem.
1. To converge on or toward a central point of focus; be focused.
2. To adjust ones vision or an optical device so as to render a clear, distinct image.
3. To concentrate attention or energy: a campaign that focused on economic issues.