'anxietude' originates from French, specifically the word 'anxiétude', where 'anxi-' is derived from Latin 'anxius' meaning 'troubled' and the suffix '-tude' (from Latin '-tudo') denoted 'state or condition'.

'anxietude' changed from the Old French word 'anxiétude' (from Latin 'anxietas') and eventually became the modern English word 'anxietude' through borrowing in the 17th–18th century.

Initially, it meant 'the state of being anxious' in much the same sense as now, but over time it has become rarer and is often considered a more literary or formal synonym of 'anxiety'.