Well, the people in the USA are using the term republic heavily till today, and the term republic is more common due to historical reasons in france. "Republic" is as common as "Democracy" in germany and the german speaking countries, the term republic is in no way uncommon today. So, i don't really see where you are coming from.

Another thing to note: Republic and constitutional monarchy or something alike aren't terms describing the actual form of government, but only the constitutional framework of the state. Democracy on the other hand is a term describing form of government, so it belongs to a different category of terms. You can have a republican democracy, a republican dictatorship, a monarchy that is democratic, a monarchy that is dictatorial and so on.