A person who forgets things; someone prone to forgetting.
From 'forget' plus the agent suffix '-er,' which creates nouns meaning 'one who does X.' This is a straightforward formation, like 'writer' (one who writes) or 'teacher' (one who teaches).
Unlike 'forgetfulness,' which is abstract, a 'forgetter' is someone you can point to—perhaps yourself! It's useful for people who want to gently self-deprecate about their memory: 'I'm a chronic forgetter of names.'
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