From Longman Dictionary of Contemporary Englishoppressorop‧pres‧sor /əˈpresə $ -ər/ noun [countable] CONTROLa person or group that treats people unfairly or cruelly, and prevents them from having the same rights that other people in society have
Examples from the Corpus
oppressor• How can they ignore that there is an oppressor and an oppressed, an occupying power and a people under occupation?• The Communists branded her a landlord and, therefore, an oppressor of peasants.• Then they become oppressors of those who do not think and act their way.• The exiled oppressor of her people had to die, and she had to be sure of it.• Instead, it is a relationship of exploiter and exploited, oppressor and oppressed.• This latter rage comes as a reflex out of denial of what the oppressors have done.• Members of the minority community view the police department as their oppressor. 