'westernise' originates from Modern English, formed from the adjective 'western' plus the verb-forming suffix '-ise' (from French '-iser', ultimately from Greek '-izein' via Latin), where 'western' meant 'of the west'.

'westernise' developed in the 19th century by applying the Greek-derived suffix '-ize'/'-ise' to 'western'. The adjective 'western' itself comes from Old English elements related to 'west' with the adjectival suffix '-ern'.

Initially it meant 'to make or become of the west' (i.e., to adopt Western traits); over time the meaning has remained largely the same but broadened to include cultural, institutional, technological, and social influences.