chad /chad/ n.
1. [common] The perforated edge strips on printer paper, after
they have been separated from the printed portion. Also called
selvage, perf, and ripoff. 2.
obs. The confetti-like paper bits punched out of cards or paper
tape; this has also been called `chaff', `computer confetti', and
`keypunch droppings'. It's reported that this was very old Army
slang, and it may now be mainstream; it has been reported seen
(1993) in directions for a card-based voting machine in
California.
Historical note: One correspondent believes `chad' (sense 2)
derives from the Chadless keypunch (named for its inventor),
which cut little u-shaped tabs in the card to make a hole when
the tab folded back, rather than punching out a circle/rectangle;
it was clear that if the Chadless keypunch didn't make them, then
the stuff that other keypunches made had to be `chad'. There is a
legend that the word was originally acronymic, standing for "Card
Hole Aggregate Debris", but this has all the earmarks of a backronym.