that's kinda like asking what kind of properties alcohol would need to exhibit to qualify as an opiate. it's similar in some ways, but the definition of "opiate" excludes alcohol.

if your definition of "psychedelic" is "drug that makes you see weird stuff", then sure, ketamine and MDMA can be psychedelics. but some people use a stricter definition based on chemistry and/or mechanism of action. under this definition, MDMA is pretty different than LSD, and ketamine is very different from both.

[[emphasis mine]]

> some people use [[a stricter definition]], based on chemistry and/or mechanism of action. under [[this definition]]

Can you please explicitly state that definition?, is what I am asking. If not, then we'd only be arguing over a vague, moving target.

I don't know of a universally accepted scientific definition. but you might find this section of the wiki page for hallucinogens helpful: https://en.m.wikipedia.org/wiki/Hallucinogen#Effects_by_type

I can see some argument for certain substances having, at the least, some adjacency to psychedelia, e.g. by way of some shared or similar mechanisms based around 5-HT receptor agonism and key involvement of the dopaminergic & serotonergic systems. But in the end we can't accurately split a hair whose bounds we can't define.

> Can you please explicitly state that definition?, is what I am asking.

The Wikipedia article[0] contains this quote:

> the term psychedelic is sometimes used more broadly to include various types of hallucinogens or those which are atypical or adjacent to psychedelia such as MDMA or cannabis; this article uses the narrower definition of psychedelics.

as well as other information on the method of action that leads to a drug being classified as a psychedelic.

I wasn't previously aware of people referring to MDMA or ketamine as "psychedelics" but I guess it might be more common than I thought. Who knew.

[0]: https://en.wikipedia.org/wiki/Psychedelic_drug