A Shiite is a Muslim who belongs to the Shia branch of Islam, one of the two main groups. The other is the Sunni. Most Muslims in the world are Sunni; Shiites are a smaller share overall, but they are a very large part of the people in countries such as Iran, Iraq, Azerbaijan, and Bahrain. The word can name a person (a Shiite) or describe something (a Shiite mosque, Shiite practice). You will also see Shia and Shi'a; they point to the same group. Learner books still teach Shiite, and news still uses it, though actually many careful writers now prefer Shia or “a Shia Muslim,” because Shiite has sometimes been thrown around in angry headlines. Use it the way you would use Catholic or Protestant: as a factual word about faith, said with respect, never as a slur. It is not a nationality and not a political party, even when politics and this branch of Islam get mixed together in the news.