noun
stronghold; base; headquarters
Refers to a main base of operations, whether a physical fortress, a military stronghold, or an organization's headquarters.
敵軍は山の本拠に立てこもった。
The enemy forces holed up in their mountain stronghold.
その企業の本拠は東京にある。
The company's headquarters is in Tokyo.
Compound of 本 (main) and 拠 (base, foothold). The exact historical derivation is uncertain, but the meaning follows naturally from the kanji components.