Definition from Wiktionary, the free dictionary
Old English tyhtan.
- (transitive) To make tighter.
- Please tighten that screw a quarter-turn.
- (intransitive) To become tighter.
- That joint is tightening as the wood dries.
- (economics) To make money harder to borrow or obtain.
- If the government doesn't tighten the money supply, inflation is certain to be harsh.
- (economics) To raise short-term interest rates.
- The Fed is expected to tighten by a quarter-point.
- (make tighter): loosen
Derived terms 
Related terms 
to make tighter
to become tighter