The story
From split (adjective) + second (noun), from split second(s) hands: see sense 1.
Etymology from Wiktionary, CC BY-SA 4.0.
split-second
split-sec·ondToday it means: A stopwatch with two second hands, each of which may be stopped separately to time the intervals of a race by a sportsperson, or to time more than one sportsperson. Full definition →