How to sign: a very short time (as the time it takes the eye blink or the heart to beat)
"if I had the chance I'd do it in a flash";
Similiar / Same: blink of an eye, jiffy, split second, trice, twinkling, wink, New York minute, heartbeat, flash
Categories: bit, minute, moment, second
How to sign: occurring with no delay
"relief was instantaneous"; "instant gratification";
Similiar / Same: instantaneous