to make a legal claim against someone, usually to get money from them because they have done something bad to you. The legal claim is called a lawsuitIf we go public with these allegations, do you think he will sue?
sue for: We intend to sue for damages.
sue someone (for something): Burnett sued the newspaper for libel and won.
sue (someone) for divorce/custody (=officially ask for a divorce or the right to keep your children): After she left him, she sued for divorce.