noun

1. a white, crystalline powder, acetylsalicylic acid, CHCOOCHCOOH, used as an anti-inflammatory drug and for reducing fever, relieving headaches, etc.
2. pl. aspirin -·rin′ or aspirins -·rins′ a tablet of this powder

Etymology: Ger < Gr a-, without + ModL Spiraea, spirea + -in: so named (1899) by H. Dreser, Ger chemist, because compounded without use of spirea (in which the natural acid is found)