— focusable , adj. — focuser , n.
/foh"keuhs/ , n. , pl. focuses, foci /-suy, -kuy/ , v. , focused, focusing or ( esp. Brit. ) focussed, focussing .
n.
1. 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. Geom. (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. See diag. under ellipse, hyperbola, parabola .
5. Geol. the point of origin of an earthquake.
6. Pathol. the primary center from which a disease develops or in which it localizes.
v.t.
7. to bring to a focus or into focus: to focus the lens of a camera.
8. to concentrate: to focus one's thoughts.
v.i.
9. to become focused.
[ 1635-45; ]
Syn. 1. center, heart, core, nucleus.