clenched fist; knuckles
Refers to a tightly closed hand, often used in contexts like hitting or threatening. Can also refer to the knuckles specifically.
He clenched his fist in anger.
He banged on the desk with his fist.
Father got angry and hit my brother with his fist.
The teacher gave the student a knock on the head with his fist.
I got a knuckle punch from my older brother after playing a prank.
He clenched his fist tightly in anger.