'tune-up' originates from 'English' as a compound of 'tune' + 'up'. The element 'tune' itself ultimately comes from Old French 'ton' and Latin 'tonus' (from Greek 'tonos') meaning 'tone' or 'sound', while 'up' comes from Old English 'up' meaning 'upward' or 'higher'.

'tune' changed from Middle English and Old French forms such as 'ton'/'toune' (meaning 'tone' or 'melody') and eventually became the modern English 'tune'; the compound 'tune-up' developed later in modern English (notably in the late 19th to early 20th century) to describe improving or adjusting machinery, especially engines.

Initially, 'tune' referred mainly to a 'musical tone' or 'melody', but over time it broadened to mean 'adjust the tone/condition' of something; consequently 'tune-up' evolved to mean 'an adjustment or maintenance to improve performance', particularly of machines.