'modernise' originates from English and French usage, specifically from the French word 'moderniser', where the root 'modern' meant 'recent' or 'of the present time' and the verbal suffix '-iser' formed verbs.

'modern' itself came into English via French 'moderne' and Italian 'moderno' from Latin 'modernus' meaning 'modern, recent'; the verb was formed in English (19th century) by adding the verb-forming suffix '-ise' (via French 'moderniser') to the adjective.

Initially it meant 'to make something recent or up-to-date', and over time it has retained that core meaning of 'making or bringing something into a modern condition'.