The generic name of an over-the-counter analgesic used to relieve fever, headache, and other pain. It is most commonly known by the trade name Tylenol. Chemical formula:
C8H9NO2
I will never take acetaminophen again as long as I live.
Of course, this may have something to do with the perils of using Tylenol as a suicide method, which alex.tan describes quite succinctly. He fails to mention that emergency room nurses hate failed suicides and put sugar in the activated charcoal, making it the most vile thing in the world to drink.
See also: Advil, aspirin, analgesic, ibuprofen, Tylenol, or the UK equivalent of acetaminophen, paracetamol.