Estates of the realm
In
France under the
ancien régime, the
Estates of the realm were the three divisions of the
Estates-General. The
First Estate was the
clergy, the
Second was
nobility, the
Third was the commoners. In theory, all commoners were part of the Third Estate. In practice, during the period where there was a division of France into estates, of the commoners only the
bourgeoisie were represented. The division of the French realm into estates was abolished during the first months of the
French Revolution.
The use of this term is not exclusive to France (although that is by far its most common usage). In Great Britain, an analogous division exists to this day, although with attenuated significance, between Lords Temporal, Lords Spiritual, and Commoners.
Note one contrast between the French and British systems: the lower clergy in France were part of the First Estate, but in Britain they are commoners.