The act or instance of betraying someone, or the state of being betrayed.
From 'betray' plus the noun-forming suffix '-ment,' which comes from Old French and Latin '-mentum.' This suffix typically indicates an action, result, or state.
The '-ment' suffix is incredibly productive in English for turning verbs into nouns—'betray' becomes 'betrayment,' just like 'manage' becomes 'management'—and we see it in Middle English texts describing historical treacheries.
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