tighten

verb

1. (transitive)To make tighter.

   “Please tighten that screw a quarter-turn.”

   “Just where I please, with tighten;d rein / I'll urge thee round the dusty plain.”

2. (intransitive)To become tighter.

   “That joint is tightening as the wood dries.”

3. To make money harder to borrow or obtain.

   “If the government doesn't tighten the money supply, inflation is certain to be harsh.”

4. To raise short-term interest rates.

   “The Fed is expected to tighten by a quarter-point.”