Sentence:  He sat for a while with his hands on his knees , watching the bend of her back as she gathered up her things - a comb , a bottle of <WSD>aspirin</WSD> - to take upstairs and pack . 
Meaning of the word marked with <WSD> tags:  the acetylated derivative of salicylic acid; used as an analgesic anti-inflammatory drug (trade names Bayer, Empirin, and St. Joseph) usually taken in tablet form; used as an antipyretic; slows clotting of the blood by poisoning platelets