Nouns

(n)republicanan advocate of a republic (usually in opposition to a monarchy)

Adjectives

(a)republicanrelating to or belonging to the Republican Party“a Republican senator”, “Republican party politics”
(s)republicanhaving the supreme power lying in the body of citizens entitled to vote for officers and representatives responsible to them or characteristic of such government“the United States shall guarantee to every state in this union a republican form of government” (United States Constitution), “a very republican notion”, “so little republican and so much aristocratic sentiment” (Philip Marsh), “our republican and artistic simplicity” (Nathaniel Hawthorne)