focus

fo•cus

[[t]ˈfoʊ kəs[/t]] n. pl. -cus•es, -ci (-sī, -kī)

1) a central point, as of attention or activity

2) phs a point at which rays of light, heat, or other radiation meet after being refracted or reflected

3) opt

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:

out of focus[/ex]

4) math. (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) gel the point of origin of an earthquake

6) pat the primary center from which a disease develops or in which it localizes

7) to bring to a focus or into focus:

to focus the lens of a camera[/ex]

8) to concentrate:

to focus one's thoughts[/ex]

9) to become focused

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Etymology: 1635–45; < L: fireplace, hearth fo′cus•a•ble, adj.