To disown someone means to formally reject them and refuse to acknowledge any connection to them anymore. When parents disown a child, they declare that person is no longer part of their family. When someone disowns a friend, they cut off the relationship completely and act as if that person never mattered to them.

The word carries a sense of finality and coldness. It's stronger than simply being angry at someone or needing space after an argument. To disown is to essentially say, “You are nothing to me now.” In historical novels, you might read about families disowning members who married against their parents' wishes or who brought shame to the family name.

People also use disown more casually to distance themselves from ideas or actions. If your friend does something embarrassing at school, you might jokingly say you're disowning them for the day. A scientist might disown an earlier theory after discovering it was wrong. In these lighter uses, the word simply means refusing to take responsibility for or be associated with something.

The opposite of disowning someone is claiming them or acknowledging them as your own, standing by them even when things get difficult.