The origin of the word ‘play’ is unknown- English adopted the word ‘pleien’ meaning to ‘dance, leap for joy, and rejoice’ from Dutch in the later Middle Ages, which was adapted as ‘pleg(i)an’, ‘to exercise, or frolic’.

To ‘play’ also adopted the meaning to amuse or divert, ‘and young and old com forth to play on a sunshine Holyday’ (c. 1638). A ‘playmate’ was used to describe children’s friends from 1642. The sexual connotation was used from 1954.

https://thecopy.team/blog/origin-word-play-copy-team-etymology-series/