What does split means in swimming?

Swimming split is a time measurement of partial distance. For example, if you are swimming 200 meters freestyle, we can measure split times for each 50 meters. Or each 25 meters. Or each 100 meters (first half split and second half split).

Split = Time measurement for a part of the distance (usually pool lenghts or laps). Swim split can also be half distance time, quarter of distance time etc.

Best example of splits come from world level competition swimming events: you are shown split times while swimmers are still swimming.

Example: In 50 meter LCM pool, on 200 backstroke event you will see time measured 4 times. After each 50 meters, swimmers will get a split time - measuring how fast they completed last 50 meters and you will get the forth, final time measurement of how long did it take for a swimmer to finish full 200 meters.

What is a negative split?

Negative split is swimming second half of the distance faster than the first one. This can be also done in quarters, meaning each quarter of the distance should we faster than the last one.