zhèng​zhōng

center

正中 zhèng​zhōng
center directional
the exact middle or central position of a physical area or object

A tall flagpole stands right in the center of the square.

nub directional
the core, essence, or central point of a matter

His analysis hit the nail on the head, identifying the biggest problem with the plan.

Frequency

Movie subtitles
4.26 per million appears in 2% of films
Written text
4.95 per million

Sources

Definitions
CC-CEDICT