'postbreakfast' originates from English, specifically the prefix 'post-' + the noun 'breakfast', where 'post-' meant 'after' and 'breakfast' meant 'a morning meal (to break a fast).'

'post-' comes from Latin 'post' meaning 'after'; 'breakfast' developed in English from the compounds 'break' + 'fast' (Old English elements meaning to end a fast). The compound 'postbreakfast' is a modern English formation using the productive prefix 'post-' and the established noun 'breakfast'.

Initially, the components meant 'after' (post-) and 'to end a fast' (breakfast); the combined modern usage simply denotes timing relative to the morning meal ('after breakfast').