Ate dinner or a formal meal, usually in a restaurant or someone's home.
From Old French 'disner', meaning to break a fast, from 'dis-' + 'jeune' (breakfast or fasting). By medieval times it referred specifically to the main meal of the day.
'Dined' has become more formal than 'ate dinner' precisely because it preserves Old French aristocratic history in its sound—we use it for special occasions to conjure that sense of refinement and celebration.
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