Sentence:  He helped Kate and Juanita enlarge the flower garden in the side yard , where they sometimes sat in the still evenings watching the last fat bees working against the <WSD>summer</WSD> 's purple dusk . 
Meaning of the word marked with <WSD> tags:  the warmest season of the year; in the northern hemisphere it extends from the summer solstice to the autumnal equinox