A person who hears or listens; one who receives or perceives sound.
From 'hear' (Old English 'hieran', to perceive sound) plus '-er', a suffix creating an agent noun for one who performs the action.
'Hearer' directly parallels 'listener,' but 'listener' has become the preferred term even though 'hearer' is technically more neutral—this shows how synonyms don't survive equally; the more specific or colorful word often outlasts the more basic one!
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