oppressor

transitive verb

1. to weigh heavily on the mind, spirits, or senses of; worry; trouble
2. to keep down by the cruel or unjust use of power or authority; rule harshly; tyrannize over
3. Obsolete
   1. to crush; trample down
   2. to overpower; subdue

Origin: ME oppressen < OFr oppresser < ML oppressare < L oppressus, pp. of opprimere, to press against < ob- (see ob-) + premere, press