Play may be defined as any voluntary and intrisnically motivated recreational activity. In game studies, it is the broader version of gameplay, which arises from playing a game.
In The Art of Game Design: A Book of Lenses, Jesse Schell discusses many possible definitions of the term before settling on "play is manipulation that indulges curiosity" (Schell 30). The concept of play helps seperate a toy from a game for Schell: a game is something someone plays; a toy is something someone plays with (37).