Nope. We're a Federal Republic, the structure and powers of which are defined and delegated by our Constitution.
You were close enough, though! Much better than 99% of the officials we've elected.
:) ttt
A Republic is a highly decentralized government, extending a majority of the powers of governace to the localities (States, Counties, etc.) Most of the nations which call themselves "Republic" are not - China, Germany (both the former DDR and the DFR).
A Federal government is a central form of government, much like the European parliamentary bodies.
Ours is a cross of both, characteristic of the opposing viewpoints which went into creating it - The jeffersonian Democratic Republicans, against the centralist Federalists. Both sides contributed to, and heavily influenced the design of our Constitition, and the viewpoints of both created the form of government which we have today, which, imho, is absolutely unique amongst the nations.
Hope this clarifies things a bit.
:) ttt