The point where rays, as of light, meet, or from which they seem to diverge.

焦点。

The focal distance.

焦距。

Sharpness of the image at the focal plane.

(在焦面上的)准度；锐度；鲜明度。

Starting point, as of infection or of an earthquake.

中心点；来源(如传染病、地震)。

One of the points whose distances form any point on a plane curve depend upon some fixed law or laws.

【数】园心。

One of the two points, as in the major axis of an ellipse, the sum of whose distances form any point on the curve is constant.

【数】椭圆或抛物线的焦点。

To centralize; concentrate.

【口】集中。

(To cause) to come to a focus.

调焦；对焦。