1a). A state or nation in which the supreme power rests in all the citizens entitled to vote (the electorate) and is exercised by representatives elected, directly or indirectly, by them and responsible to them.
1b). The form of government of such a state or nation.
2. Any group whose members are regarded as having a certain equality, common aims, etc.: as the republic of letters.
3. A state or nation with the president as its titular head; distinguished from monarchy.
From Webster’s New World Dictionary of the American Language
College Edition
World Publishing Country
Cleveland and New York
1968