Radical
贝 (cowrie shell, the ancient currency) signals a money-related meaning — same family as
财 (wealth),
贵 (expensive),
贪 (greed).
贿 itself is bound: you'll see it in
行贿 (offer a bribe),
受贿 (accept a bribe),
贿赂 (bribe, full word),
索贿 (demand a bribe).
