Relating to or formed by episyntheton; characterized by the formation of compound words or constructions added upon or attached to existing words.
From Greek 'epi-' (upon) + 'synthetic' (put together), describing language construction that adds or builds upon existing word forms.
English does this constantly—we take 'happy' and add 'un-' to get 'unhappy,' then add '-ness' to get 'unhappiness'—building up one layer at a time.
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