This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. Sports A room or building equipped for indoor sports.

n. Sports An academic high school in some central European countries, especially Germany, that prepares students for the university.

n. A large room or building for indoor sports.

n. A type of secondary school in some European countries which typically prepares students for university.

n. A place or building where athletic exercises are performed; a school for gymnastics.

n. A school for the higher branches of literature and science; a preparatory school for the university; -- used esp. of German schools of this kind.

n. In Greek antiquity, a public place for instruction in and the practice of athletic exercises: a feature of all Greek communities.

n. Hence In modern use, a place where or a building in which athletic exercises are taught and performed.

n. A school or seminary for the higher branches of literature and science; a school preparatory to the universities, especially in Germany; a classical as opposed to a technical school.

n. athletic facility equipped for sports or physical training

n. a school for students intermediate between elementary school and college; usually grades 9 to 12

"The word gymnasium comes from the Greek word gymnos, which means naked."

athletic facility   

gym    gymnastics   

gymnasia   

calisthenium    gymkhana    palaestra    palestra   

gym    cafeteria    auditorium    theaters    dormitory    museum    playroom    clinic    schoolroom    laboratory