Desertion of a party, cause, principle, etc. Formerly with over.

The qualities or conduct of a ratter; abandonment of parties, causes, principles, etc. Obsolete.

The behaviour and practices of a renegade.

the institution of segregation, the practice of ‘racial’ discrimination; (also) the act of deserting one's political party.

A sudden starting off; making off, running away, flight; (in U.S. Politics) sudden secession from a political party.