1 [uncountable and countable]
when someone is not allowed to take part in something or enter a place [≠ inclusion]
the country's exclusion from the United Nations
2 [uncountable and countable] British English
when a child is officially made to leave their school because of their bad behaviour
to do something so much that you do not do, include, or have time for other things:
Your essays tend to concentrate on one theme to the exclusion of everything else.
something that is excluded from a contract [≠ inclusion]:
You will be sent full details of the exclusions of your insurance policy.
exclusionary business practices