Sunlit means lit by direct light from the sky. A sunlit room, sunlit uplands, sunlit water.
It describes the light rather than the weather, so a cold day can have sunlit rooms. It is a warm word and mostly used in description. Sunlit uplands is a fixed political phrase for a promised better future, originally from Churchill and now used more often sarcastically than not. Note sunlight; and that lit is the past participle of light.
1adjectivesunlitLit by direct light from the sky.
“We ate breakfast in a sunlit corner of the garden.”
sunlit is a quality of lighting.
Sun plus lit, the past participle of light. English forms these freely — moonlit, candlelit, floodlit.
From sun + lit.
Etymology from Wiktionary, CC BY-SA