Howl vs Undefined - What's the difference?

As a noun howl

is the protracted, mournful cry of a dog or a wolf, or other like sound.

is to utter a loud, protracted, mournful sound or cry, as dogs and wolves often do.

lacking a definition or value.

(en noun)

The protracted, mournful cry of a dog or a wolf, or other like sound.

A prolonged cry of distress or anguish; a wail.

(en verb)

To utter a loud, protracted, mournful sound or cry, as dogs and wolves often do.

* Drayton

And dogs in corners set them down to howl .

* Shakespeare

Methought a legion of foul fiends / Environ'd me about, and howled in my ears.

To utter a sound expressive of pain or distress; to cry aloud and mournfully; to lament; to wail.

* Bible, Isaiah xiii. 6

Howl ye, for the day of the Lord is at hand.

To make a noise resembling the cry of a wild beast.

* Sir Walter Scott

Wild howled the wind.

To utter with outcry.

to howl derision

(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