Tighten vs Undefined - What's the difference?

As a verb tighten

is to make tighter.

lacking a definition or value.

(en verb)

To make tighter.

Please tighten that screw a quarter-turn.

* Fawkes

Just where I please, with tightened rein / I'll urge thee round the dusty plain.

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

* retighten * tighten one's belt * tighten the purse strings * tightener

* titan, Titan

(wikipedia undefined) (-)

Lacking a definition or value.

(mathematics, computing) That does not have a meaning and is thus not assigned an interpretation.

The result of division by zero is undefined .

* defined