'headache' originates from Old English, specifically the words 'heafod' (meaning 'head') and 'æce' (meaning 'ache' or 'pain').

'headache' developed in Old English as a compound of 'heafod' + 'æce', appeared in Middle English in forms like 'hede ache' or 'head ache', and eventually became the single-word modern English 'headache'.

Initially it referred specifically to physical pain in the head ('pain in the head'), and over time it also took on figurative senses such as 'a nuisance or problem'.