noun
federal system
Refers to a political system in which power is divided between a central authority and constituent political units (states, provinces, etc.).
アメリカは連邦制を採用している。
The United States adopts a federal system.
連邦制の下では、州ごとに法律が異なることがある
Under a federal system, laws can differ from state to state.
中央集権 means 'centralization of authority', which is the opposite of a federal system where power is distributed.
Compound of 連邦 (れんぽう, 'federation') + 制 (せい, 'system'). The term is a straightforward Sino-Japanese construction.