Overlook vs Undefined - What's the difference?

As a noun overlook

is a vista or point that gives a beautiful view.

is to look down upon from a place that is over or above; to look over or view from a higher position; to rise above, so as to command a view of.

lacking a definition or value.

(Webster 1913)

(en noun)

A vista or point that gives a beautiful view.

(en verb)

To look down upon from a place that is over or above; to look over or view from a higher position; to rise above, so as to command a view of

to overlook a valley from a hill

Hence: To supervise; to watch over; sometimes, to observe secretly

to overlook a gang of laborers; to overlook one who is writing a letter

To inspect; to examine; to look over carefully or repeatedly.

To look upon with an evil eye; to bewitch by looking upon; to fascinate.

To fail to notice; to look over and beyond (anything) without seeing it; to miss or omit in looking.

To pretend not to have noticed, especially a mistake; to pass over without censure or punishment.

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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