Paucity vs Undefined - What's the difference?

As a noun paucity

is fewness in number; too few.

lacking a definition or value.

Fewness in number; too few.

* 1915 , , The Golden Slipper , problem 7:

But when I had crossed the threshold, I was astonished at the paucity of facts to be gleaned from the inmates themselves.

* 2006 , Po Bronson and Ashley Merryman, " Uncle Sam Wants You," Time , 13 July:

Your tax refund might be late, owing to a paucity of number crunchers.

A smallness in size or amount that is insufficient; meagerness, dearth.

* 1898 , , "At the Appetite-Cure":

Now came shipwrecks and life in open boats, with the usual paucity of food.

* 1915 , , Michael O'Halloran , ch. 12:

Here is where the paucity of our language is made manifest.

* dearth, scantiness, scarcity

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(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