The word "sue" refers to the act of taking legal action against someone in a court of law. When a person sues another, they are seeking a legal remedy or compensation for a perceived wrong, such as a breach of contract, personal injury, or discrimination.
The word "sue" comes from Old French "suer" meaning "to follow" or "to seek". This, in turn, derives from the Latin "sequi", which means "to follow". The legal usage of the term originated in the Middle Ages.