'purulent' originates from Latin, specifically the Late Latin word 'purulentus', where the element 'pur-' is associated with 'pus' (Latin 'pus, puris') meaning 'pus'.

'purulent' changed from the Late Latin word 'purulentus' (used in medical Latin) and eventually entered English as the modern word 'purulent' via learned/medical usage.

Initially, it meant 'full of or producing pus', and over time it has retained this medical meaning in English.