| 1. | a fraction of a second. |
| 2. | an infinitesimal amount of time; instant; twinkling. |
| split second n. An instant; a flash. [Short for split second hands, a stopwatch with two second hands, one beneath the other, one of which may be stopped independently of the other.] |
split second
An instant, a fraction of a second, as in Our best swimmer came in a split second before theirs. This expression alludes to a stop watch that has two second hands, one above the other, for timing more than one athlete or intervals of a race by a single athlete. Each hand can be stopped independently of the other, so a second can be "split" when one second hand stops a fraction of a second after the other. [c. 1880]