jiffy: n. 1. The duration of one tick of the system clock on the computer (see {tick})

:jiffy: n. 1. The duration of one tick of the system clock on the
computer (see {tick}). Often one AC cycle time (1/60 second in
the U.S. and Canada, 1/50 most other places), but more recently
1/100 sec has become common. "The swapper runs every 6 jiffies"
means that the virtual memory management routine is executed once
for every 6 ticks of the clock, or about ten times a second.
2. Confusingly, the term is sometimes also used for a 1-millisecond
{wall time} interval. Even more confusingly, physicists
semi-jokingly use `jiffy' to mean the time required for light to
travel one foot in a vacuum, which turns out to be close to one
*nanosecond*. 3. Indeterminate time from a few seconds to
forever. "I'll do it in a jiffy" means certainly not now and
possibly never. This is a bit contrary to the more widespread use
of the word. Oppose {nano}. See also {Real Soon Now}.
-- The AI Hackers Dictionary