classmate; person in the same year group
Refers to someone who entered a school, company, or organization in the same year, or graduated together. Broader than just a classmate; it emphasizes the shared cohort.
He is a classmate from university.
I attended training together with my fellow new hires.
sumo wrestler who debuted in the same tournament
Sumo-specific term for wrestlers who began their professional careers in the same tournament. Not used in everyday conversation.
He is my fellow debutant; we first stepped into the ring at the same tournament.