Useless vs Undefined - What's the difference?

As adjectives the difference between useless and undefined

is that useless is without use or possibility to be used while undefined is lacking a definition or value.

(en-adj)

Without use or possibility to be used.

This fork has prongs that are bent. It's useless now.

Unhelpful, not useful; pointless (of an action).

I think it's useless to keep this discussion going. It's like talking to a wall.

I tried my best to make him quit smoking, but my efforts were useless . He now smokes six packs a day.

(pejorative, of a person) good-for-nothing; not dependable.

Bill never mows the lawn, takes out the trash or anything. He's useless , but I love him anyways.

(colloquial, of a person) unable to do well at a particular task or thing. Useless is mildly insulting.

My brother is useless at most computer games, but he is an awesome PS2 player.

Why do you keep trying? You're obviously useless at it.

* (good-for-nothing) good-for-nothing * (unable to do well) unskillful

* skillful, useful

* uselessly * uselessness

(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