tennis – теннис, см. «tenet»

tennis (n.) (из англо-французского «tenetz» - держи, получи; из старофранцузского «tenez»; из «tenir» - держи, получи, которое использовалось как обращение к противнику; изначально игра средневековых французских рыцарей; по мячу били ладонями
mid-14c., most likely from Anglo-French tenetz "hold! receive! take!," from Old French tenez, imperative of tenir "to hold, receive, take" (see tenet), which was used as a call from the server to his opponent. The original version of the game (a favorite sport of medieval French knights) was played by striking the ball with the palm of the hand, and in Old French was called la paulme, literally "the palm," but to an onlooker the service cry would naturally seem to identify the game.