A person who abandons, deserts, or gives up someone or something they were previously committed to.
From 'forsake' + '-er' (agent noun suffix). The '-er' ending makes an active agent noun from the verb, indicating the person who performs the action of forsaking.
In medieval literature, a 'forsaker' was worse than a coward—they were a betrayer who had made promises then broken them, which was considered a moral crime.
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