Meaning of 握拳 in Japanese

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Definition of 握拳

にぎる(nigiru) 【握る】

(v5r, vt) to clasp; to grasp; to grip; to clutch
彼らが眠っている間私がハンドルを握った。
I took the wheel while he slept.
to make (nigirizushi, rice ball, etc.); to form; to press into shape; to mold; to mould
to seize (power, etc.); to take hold of

こぶし(kobushi) 【拳】

けん(ken) 【拳】