1 become/make sth firmer/tighter
ADV. fractionally, a little, slightly | convulsively, involuntarily Her fingers tightened convulsively with every jolt she received. | painfully | up Can you tighten up the bolts for me?
VERB + TIGHTEN seem to | feel sth, sense sth He felt his stomach tighten. | make sth His words made her throat tighten.
PREP. about/around/round His hand tightened painfully around her wrist. | on Her grip seemed to tighten on the door handle. | in He saw his father's jaw tighten in irritation. | into His mouth tightened into a thin hard line. | with Her face tightened with pain.
2 make sth more strict
VERB + TIGHTEN take steps to Steps were taken to tighten discipline in the school.
PREP. up The law in this area has been tightened up considerably.