- Psychoactive drugs: chemicals that change conscious awareness or perception
- Dependence: relying on drugs
- Withdrawal: physical reaction from ceasing to take addictive drug
- Tolerance: more drug required for effect
- Depressants: reducing nerve activity
- Stimulants: stimulating nerve activity
- Narcotics: mimic endorphins
- Hallucinogens: cause hallucinations
- Physical dependence: physiological symptoms from withdrawal
- Psychological dependence: psychological symptoms from withdrawal
- Agonist: mimics neurotransmitter
- Antagonist: inhibits reuptake