'postpyretic' originates from English, formed from the Latin prefix 'post-' meaning 'after' combined with 'pyretic' from Greek 'pyretos' meaning 'fever'.

'pyretic' derives from Greek 'pyretos' ('fever'), passed into Late Latin as 'pyreticus' and then into English as 'pyretic'; the compound 'postpyretic' is a later English formation using the productive prefix 'post-'.

Initially, 'pyretic' meant 'pertaining to fever'; the modern compound 'postpyretic' specifically denotes 'after a fever' rather than 'relating to fever' itself.