Asking what a class a chemical belongs to is like asking someone what their favorite color is: it's a matter of opinion. I'd call it a drug, because I think "spirits" describe alcoholic drinks.
And to confirm what the previous posters said, LSD is not physically addictive, and also is also NOT LIKELY to be psychologically addictive. From my experience, it is neither. However, I would also say that it is not "a bad drug to take." I disagree with that statement, but because of the forum restrictions, I can't say that it IS a good drug.
PhD student - Organic Chemistry
I don't read an entire thread before I respond; I try to answer the question quickly and concisely.