Brownie vs Undefined - What's the difference?

As a noun brownie

is (britain|canada|australia) a junior girl guide.

lacking a definition or value.

(wikipedia brownie) (Chocolate brownie)

(en noun)

A small square piece of rich cake, usually made with chocolate.

* 2000 , , Stick Figure: a diary of my former self , page 173,

if she ever found out she was dying, she'd just eat brownies all day and night until the very end.

* 2005 , Aaron Lazare, On Apology , unnumbered page,

On a Saturday afternoon, my wife bought her favorite treat for dessert that evening, a gourmet, nut-filled brownie .

* 2005 , Steve Otto, Memoirs of a Drugged-Up, Sex-Crazed Yippie , page 228,

After cooking the brownies' until we could smell the pot, we each ate a large ' brownie .

(folklore) A mythical creature, a helpful elf who would do people's housework for them.

* 1908', , '' The Adventures of A '''Brownie .

* 1985 , The Encyclopedia Americana , Volume 1, page 636,

Stories were told of a brownie riding horseback to fetch the midwife at childbirth or helping his master to win at checkers.

* 2004 , Justin Hocking, Jeffrey Knutson, Jared Jacang Maher (editors), Life and Limb: Skateboarders Write from the Deep End , page 37,

There are no brownies in my house, though. I know because there's always a pile of dishes in the sink.

(paganism) A household spirit or revered ancestor.

(Australia, New Zealand, colloquial) A tall, long-necked beer bottle, made from brown coloured glass.

(ethnic slur, offensive) A person of Arab, Indian or Hispanic descent. Also rarely used for a Native American or Pacific Islander.

* chocolate brownie * hash brownie

(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