1) A frequent user of the drug DXM (dex), which comes in cough syrup. If ingested in high amounts, DXM can produce hallucinogens and euphoric feelings.
2) Used in reference to a person who is generally spaced out, or oblivious to his or her surroundings.
1) My friend is such a dexhead! He just bought two more bottles of nyquil, and he's tripping on the shit right now!
2) That kid on my bus was just staring out the window when Ashley was trying to talk to him. What a dexhead.
A person who frequently abuses the drug Dextromethorphan.
I am a Dexhead.