intramural
Happening only within one school or organization.
Intramural means happening within a single school or organization.
Most commonly, you'll hear about intramural sports: teams from the same school competing against each other rather than against other schools. If your elementary school has an intramural basketball league, fifth graders might form different teams that play against each other during lunch or after school. Everyone plays for fun and exercise, not to win championships against rival schools. That would be interscholastic or extramural competition (between schools).
Intramural activities give more students a chance to participate since the competition isn't as intense as varsity sports. A student who wouldn't make the school's travel soccer team might enjoy playing in an intramural league where the focus is on learning skills and having fun with classmates.
The word can describe anything that happens within one institution: an intramural debate between different classes, or intramural mail that travels between offices in the same building. Think of intramural as meaning “in-house”: it stays within your own school or organization rather than going outside to compete or interact with others.