n.

1. 焦点，焦距；聚光点[C]
   He took out the binoculars and adjusted the focus.

   他取出双筒望远镜并调整了焦距。

2. 调焦；聚焦[U]
3. 成像清晰点；（图像的）清晰；明确[U]
4. （注意，活动等的）中心，集中点；重点[the S][（+of）]
   The focus of this chapter is the American Revolution.

   本章的重点是讲美国独立战争。

   She always wants to be the focus of attention.

   她老想成为人们注意的中心。

5. （地震等的）震源；病灶
   The focus of the earthquake is eighty miles from our city.

   这次地震的震源在距我市八十英里的地方。

vt.

1. 使聚焦[（+on）]
2. 调节（镜头等）的焦距[（+on）]
   You can focus your telescope on that distant television tower.

   你可以对着那座远方的电视塔调节望远镜的镜头。

3. （调节镜头的焦距）使（图像等）清晰
4. 使集中[（+on）]
   I can't focus my thoughts today.

   今天我的思想集中不起来。

vi.

1. 聚焦
   A defect of vision prevented him from focusing accurately.

   视力上的缺陷使他不能准确对焦。

2. 调节焦距[（+on）]
3. 集中[（+on）]
   The beams of light moved across the sky and focused on the plane.

   光束在空中移动，集中对准飞机。

n.

1. the centre of interest or activity.
   ▸an act of focusing on something.
2. the state or quality of having or producing clear visual definition.
   ▸another term for focal point.
   ▸the point at which an object must be situated with respect to a lens or mirror for an image of it to be well defined.
3. Geology  the point of origin of an earthquake. Compare with epicentre.
4. Medicine  the principal site of an infection or other disease.
5. Geometry  one of the fixed points from which the distances to any point of an ellipse, parabola, or other curve are connected by a linear relation.
6. Linguistics  an element of a sentence that is given prominence by intonational or other means.

v.

1. adapt to the prevailing level of light and become able to see clearly.
   ▸adjust the focus of (a telescope, camera, etc.).
   ▸(of rays or waves) meet at a single point.
   ▸(of light, radio waves, or other energy) become concentrated into a sharp beam of light or energy.
2. (focus on) pay particular attention to.
3. Linguistics  place the focus on (a part of a sentence).