When someone shows sportiveness, they are being playful and having fun, especially during a game or physical activity.
Sportiveness is usually seen as a good thing because it means someone is enjoying themselves and being friendly.
Examples:
Her sportiveness during the game made everyone smile.
I like to play with sportiveness.
Sportiveness is important in sports.
The cat showed sportiveness when it played with the ball.
His sportiveness during the race was contagious.
The dog's sportiveness was the highlight of the party.