to govern people in an unfair and cruel way and prevent them from having opportunities and freedom

For years now, the people have been oppressed by a ruthless dictator. 多年来，人们一直处于残暴的独裁者的压迫之下。

to make a person feel uncomfortable or worried, and sometimes ill

Strange dreams and nightmares oppressed him. 怪梦和噩梦使他感到焦虑不安。