Acid-head is a slang term that is often used to describe a person who frequently uses LSD or other hallucinogenic drugs. However, using this term can be offensive and insensitive. There are many alternative terms that can be used instead of acid-head. Words like tripper, psychedelic explorer, psychonaut, or mind traveler are some of the synonyms that can be used to describe someone who is interested in the psychedelic experience. It is important to remember that language has the power to shape attitudes and perceptions, so it's essential to use respectful and non-judgmental language when talking about people who use drugs.