'aguish' originates from the word 'ague', which comes from the Old French 'ague', derived from the Latin 'acuta', meaning 'sharp' or 'acute'.

'ague' transformed from the Old French 'ague' and eventually became the modern English word 'ague', with 'aguish' being derived as an adjective form.

Initially, 'ague' referred to a fever with chills, and 'aguish' described the symptoms associated with it. This meaning has largely remained the same in modern usage.