Lysergic Acid Diethylamide Tartrate, commonly known as LSD, is a potent hallucinogenic drug that causes altered states of consciousness. Antonyms for this word might include "sober," "unaffected," "inert," "unintoxicated," "unstimulated," and "unaffected." Other potential antonyms might include scientific terms such as "benign," "placebo," and "control," or legal terminology such as "forbidden," "prohibited," or "illegal." In any case, LSD is a powerful and potentially dangerous drug, and anyone considering experimenting with it is advised to seek professional medical advice and guidance first.