鉄則

てっそく
ironclad regulation
inviolable rule

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てっそく【鉄則】

(hard-and-)fast rule

〖C〗.

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てっそく【鉄則】

an ironbound [ironclad] rule; a hard and fast rule; an invariable principle.

●働かざるもの食うべからずが人の世の鉄則だ. No work, no pay is the rule in this world.