1 the sun, the Sun [singular] the star that shines in the sky during the day and gives the earth heat and light the sun’s rays the rising/setting sun The sun was shining and birds were singing. The sun was just setting. A pale wintry sun shone through the clouds.2 (also the sun) [singular, uncountable] the light and heat from the sun the warmth of the afternoon sun This room gets the sun in the mornings. We sat in the sun. The sun was blazing hot. Too much sun ages the skin. We did our best to keep out of the sun. They've booked a holiday in the sun (= in a place where it is warm and the sun shines a lot). Her face had obviously caught the sun (= become red or brown) on holiday. I was driving westwards and I had the sun in my eyes (= the sun was shining in my eyes).