Romanism
Romanism is a derogatory term for Roman Catholicism used when anti-Catholicism was more common in the United States. The word was first attested in 1603.
The term was frequently used in late-nineteenth and early-twentieth century Republican invectives against the Democrats, as part of the slogan "Rum, Romanism, and Rebellion" (referencing the Democratic Party's constituency of Southerners and anti-Temperance, frequently Catholic, working-class immigrants). A book titled "The Three Keys to Hell; or, Rum, Romanism and Ruin" was published in 1915. The term and slogan gained particular prominence in the 1884 presidential campaign and again in 1928, in which the Democratic candidate was the outspokenly anti-Prohibition Catholic Governor of New York Al Smith.
In Northern Ireland, the term was also used by Democratic Unionist Party founder Ian Paisley in anti-Catholic speeches.