'full-colour' originates from Old English and Old French/Latin, specifically the words 'full' (Old English 'full') and 'colour' (Old French 'colour', from Latin 'color'), where 'full' meant 'filled' and 'color' meant 'hue, appearance'.

'full-colour' changed from the Middle English phrase (e.g. 'ful colur' / 'full colour') and eventually became the modern English compound 'full-colour' (with variant spelling 'full-color' in American English).

Initially, it meant 'completely filled with colour' (a direct descriptive compound), and over time it has retained that core sense to refer to images, printing, or representation presented in complete/vivid colour.