'sunlit' originates from the combination of 'sun' and the past participle 'lit' of the verb 'light', where 'sun' refers to the star at the center of our solar system and 'lit' means 'illuminated'.

'sunlit' changed from the Old English word 'sunnan' (sun) and 'lyht' (light) and eventually became the modern English word 'sunlit'.

Initially, it meant 'illuminated by the sun', and this meaning has largely remained the same in modern usage.