'dux' originates from Latin, specifically the word 'dux', where the root 'duc-' (from the verb 'ducere') meant 'to lead'.

'dux' came into English usage from Latin (and via Medieval/Church Latin use); related forms in Romance languages include Old French 'duc' (which yielded English 'duke'), while the Latin noun 'dux' continued to be used in learned and institutional contexts and eventually as the English form 'dux' for certain usages.

Initially it meant 'leader' or 'commander' in Latin, and this core meaning has been retained in English; additionally, in some regional educational systems it developed the specialized meaning 'the school's top pupil'.