'dehumanise' originates from the prefix 'de-' (from Latin 'de-' meaning 'remove' or 'reverse') combined with the verb 'humanise', which ultimately comes from Latin 'humanus', where 'human-' meant 'human' or 'humane'.

'dehumanise' developed as a negative formation of 'humanise/humanize' (from late Latin 'humanizare' via French 'humaniser'), and the English negative form 'dehumanise/dehumanize' appeared in modern usage in the 19th–20th century.

While 'humanise' originally meant 'to make humane' or 'to give human qualities', the prefixed form 'dehumanise' came to mean 'to remove human qualities' or 'to treat someone as less than human'.