'RINO' originates from the English phrase 'Republican In Name Only', where 'Republican' refers to a member of the Republican Party and 'In Name Only' implies a lack of genuine adherence to the party's principles.

The term 'RINO' emerged in the late 20th century as a political label within the United States.

Initially, it was used to criticize Republicans who were perceived as too liberal, and this meaning has largely remained the same in modern usage.