1. n. a headache. Music that loud gives me a head.
2. and a head n. a hangover. (Always with a in this sense.) How do you get rid of a head so you can go to work?
3. n. a toilet; a restroom. (Originally nautical. Usually with the.) Ralph is in the head. He’ll be back in a minute.
4. n. a member of the drug culture; a hippie or a person who drops out of mainstream society because of drug use. (From the 1960s and 1970s.) You still see a few heads around, even today.
5. n. a smart person; an intellectual person. I’m no head, but I am sure you made a mistake in your addition.