Rot vs Undefined - What's the difference?

As a noun rot

is meat roasted on a spit.

lacking a definition or value.

(rott)

To suffer decomposition due to biological action, especially by fungi or bacteria.

* Alexander Pope

Fixed like a plant on his peculiar spot, / To draw nutrition, propagate, and rot .

To decline in function or utility.

To deteriorate in any way.

I hope they all rot in prison for what they've done.

* Macaulay

Four of the sufferers were left to rot in irons.

* Thackeray

Rot , poor bachelor, in your club.

To make putrid; to cause to be wholly or partially decomposed by natural processes.

to rot vegetable fiber

To expose, as flax, to a process of maceration, etc., for the purpose of separating the fiber; to ret.

* potter's rot

(en noun)

The process of becoming rotten; putrefaction.

Any of several diseases in which breakdown of tissue occurs.

* Milton

His cattle must of rot and murrain die.

Verbal nonsense.

* (nonsense) See also

* (l), (l), (l), (l), (l), (l), (l) English intransitive verbs ----

(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