The sidestroke is a swimming stroke, so named because the swimmer lies on one's side with asymmetric arm and leg motion. It is helpful as a lifesaving technique and is often used for long-distance swimming.

The meaning of SIDESTROKE is a swimming stroke which is executed on the side and in which the arms are swept in separate strokes towards the feet and downward and the legs do a scissors kick.

Side stroke is an old swimming style formerly used in competitive swimming from 1800s to 1900s. Today, it's primarily used as a rescue swimming style as lifeguards and navy seals widely use it. The name of this swimming stroke is pretty self-explanatory, as it's performed on the side.