/ ˈtaɪtn; NAmE / verb tighten (sth) (up)
1.
to become or make sth become tight or tighter :
[ v ]
The rope holding the boat suddenly tightened and broke.
His mouth tightened into a thin line.
[ vn ]
to tighten a lid / screw / rope / knot
The nuts weren't properly tightened and the wheel came off.
She tightened her grip on his arm.
2.
[ vn ] to make sth become stricter :
to tighten security
OPP loosen
•
IDIOMS
- tighten your belt
•
PHRASAL VERBS
- tighten up (on sth)