(1) The time between a traffic light turning green and New York City drivers blowing their horn. Of course, the real definition is (2)!
(2) One billionth of a second. Used to measure the speed of logic and memory chips, a nanosecond can be visualized by converting it to distance. In one nanosecond, electricity travels within a wire approximately one foot. Rear Admiral Grace Hopper was known for handing out strands of "telephone wire nanoseconds" to her audience whenever she lectured about technology. Holding the wire turns the unreal concept of a billionth of a second into physical reality. See
Grace Hopper Superchip.
Even at 186,000 miles per second, electricity is never fast enough for the hardware designer who worries over the length of a circuit path. The slightest delay is multiplied millions of times, since billions of pulses are sent through a wire in a single second. In addition, today's state-of-the-art chips can contain more than 25 miles of wire traces, which are the circuit pathways that carry electricity. See
space/time,
jiffy and
ohnosecond.