Invent vs Undefined - What's the difference?

As a verb invent

is to design a new process or mechanism.

lacking a definition or value.

(en verb)

To design a new process or mechanism.

After weeks of hard work, I invented a new way to alphabetize matchbooks.

To create something fictional for a particular purpose.

I knew I had to invent an excuse, and quickly.

We need a name to put in this form, so let's just invent one.

(obsolete) To come upon; to find; to find out; to discover.

* 1590 , Edmund Spenser, The Faerie Queene , I.vi:

Far off he wonders, what them makes so glad, / If Bacchus merry fruit they did inuent [...].

* fangle * discover

* * 1000 English basic words

(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