'rouge' originates from French, specifically the Old French word 'rouge' (or 'roge'), where the root meant 'red' (from Latin-related roots).

'rouge' passed into Middle English from Old French 'rouge' meaning 'red' and later came to refer also to the cosmetic used to redden the cheeks; this Old French term itself is ultimately related to Latin roots such as 'ruber'/'rubeus' meaning 'red'.

Initially it meant 'red' (the color), but over time it evolved to also mean 'a cosmetic used to redden the cheeks' in English.