A person who condones; someone who forgives, excuses, or overlooks wrongdoing.
From 'condone' + the suffix '-er' (indicating an agent noun, one who performs the action). English freely creates agent nouns from verbs to describe people by what they do.
A 'condoner' is someone whose character involves forgiving—it's a way of describing a person's pattern of behavior, which can be seen as either compassionate or frustratingly permissive depending on the context.
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