split second

/splɪt ˈsɛkənd/

Other forms: split seconds

A moment so short it can barely be measured, like the time it takes to blink, is called a split second. A birdwatcher may catch sight of a hummingbird, only to have it disappear a split second later.

You can also call a split second a heartbeat or a flash. This term emphasizes how brief something is: "I only paused a split second before volunteering for the spelling bee." It can also be an adjective, as in "split second timing" or a "split second decision." The original split second was a type of stopwatch with two second hands, so that a fraction of a second could be timed.

Definitions of split second

1. noun

   a very short time (as the time it takes the eye to blink or the heart to beat)
   synonyms: New York minute, blink of an eye, flash, heartbeat, instant, jiffy, trice, twinkling, wink

   type of:

   bit, minute, mo, moment, second

   an indefinitely short time