/ klentʃ; NAmE / verb
1.
when you clench your hands, teeth, etc., or when they clench , you press or squeeze them together tightly, usually showing that you are angry, determined or upset :
[ vn ]
He clenched his fists in anger.
Through clenched teeth she told him to leave.
[ v ]
His fists clenched slowly until his knuckles were white.
2.
[ vn ] clench sth (in / between sth) to hold sth tightly and firmly :
Her pen was clenched between her teeth.
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WORD ORIGIN
Old English (in the sense of clinch fix securely ): of Germanic origin; related to cling .