sidestroke
noun
side·stroke ˈsīd-ˌstrōk 
: 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
Example Sentences
Recent Examples on the Web Morgan learned how to rely on the sidestroke and breaststroke, so his legs and arms never broke the surface of the water. 
Andrew Dubbins, Smithsonian Magazine, 18 Aug. 2022
Andrew Dubbins, Smithsonian Magazine, 18 Aug. 2022 Word History
First Known Use
1852, in the meaning defined above