Singed vs Undefined - What's the difference?

As a verb singed

is (singe).

lacking a definition or value.

(head)

(singe)

* * *

(d)

To burn slightly.

* L'Estrange

I singed the toes of an ape through a burning glass.

To remove the nap of (cloth), by passing it rapidly over a red-hot bar, or over a flame, preliminary to dyeing it.

To remove the hair or down from (a plucked chicken, etc.) by passing it over a flame.

* scorch

(en noun)

A burning of the surface; a slight burn.

* ----

(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