'pusillanimous' originates from Latin, specifically the word 'pusillanimis', where 'pusillus' meant 'very small' and 'animus' meant 'spirit'.

'pusillanimous' changed from the Latin word 'pusillanimis' (used in Late Latin), passed into English through learned borrowings in the 16th–17th centuries, and eventually became the modern English word 'pusillanimous'.

Initially, it meant 'having a small spirit' or 'very small-minded', but over time it evolved into its current meaning of 'lacking courage or resolution'.