'deaden' originates from Old English elements: the adjective 'dead' plus a verb-forming suffix '-en', where 'dead' meant 'lacking life' and '-en' meant 'to make or become'.

'dead' (Old English 'dēad') combined with a verb-forming element (Old English/Germanic '-ian'/'-en') in Middle English to form verbs such as 'deaden', which eventually became the modern English 'deaden'.

Initially it meant 'to make dead' (literally causing death), but over time it broadened to include 'to make lifeless, dull, numb, or less intense' in both literal and figurative senses.