Jiffy is very short time span like a flash. Just wait for a jiffy!

Yet, Jiffy is the unit of time! And what is astonishing, Jiffy is the most flexible unit of time like the Time itself.

It has long enough history since 18th century. In different application and in different times Jiffy had different amounts.

In computer applications, in particular, in Linux kernel it is varied between about 1 ms and 10 ms.  Wonder! Precise math talk operates with so much approximate value.  It looks like the Time has becoming faster not only in social life but even in scientific applications.

See Jiffy on WikiPedia.