Tenniser
A person who performs or plays in the act of tennis.
She was a pro tenniser, making it to state championship.
Tennising
The act of playing tennis in the past verb tense. Can also be used in the present progressive.
Jack: Hey what are you doing after school?
Kate: Oh I don't know, maybe some tennising?
Jack: Are the courts open?
Kate: Yeah I'm pretty sure they are.
Kate: Oh I don't know, maybe some tennising?
Jack: Are the courts open?
Kate: Yeah I'm pretty sure they are.
tennising
When two guys are simultaneously sex with a girl and she bounces inside of one to the other, much like a tennis ball going back and forth.
Person 1: Hey, Brad and I were tennising this girl last night so hard, she bounced off the bed!
Person 2: Brad, you are such a douchebag.
Person 2: Brad, you are such a douchebag.