'sixties-style' originates from English, specifically the compound of 'sixties' (the decade 'sixties') and 'style' (manner or fashion).

'sixties' is formed from the numeral 'sixty' + plural '-s'; 'sixty' comes from Old English 'sixtig' (or 'sixty'), ultimately from Proto-Germanic roots for 'six' + a tens suffix. 'style' comes from Latin 'stilus' (writing instrument/point) via Old French 'style' and Middle English to mean 'manner' or 'mode', and the compound 'sixties-style' arose in Modern English to describe the characteristic style of the 1960s.

Initially used simply to link the decade ('sixties') with 'style' to denote something of or relating to that decade; it has retained that basic meaning and is used broadly for fashion, design, music, and cultural aesthetics evoking the 1960s.