1. 焦点;(关注)中心
The focal point of something is the thing that people concentrate on or pay most attention to.

1. the concentration of attention or energy on something

e.g. the focus of activity shifted to molecular biology
he had no direction in his life

Synonym: focusfocusingfocussingdirectioncentering

2. a point of convergence of light (or other radiation) or a point from which it diverges

Synonym: focus

3. a central point or locus of an infection in an organism

e.g. the focus of infection

Synonym: focusnidus