So sprayed metal particles from airplanes for weather modification are only "chemtrails" if it's done covertly.

Language sure is interesting.

I guess there's also a spectrum of what covert means. If a government does this but only announces it in places where only a few people hear about it from the official source, I guess that still counts as public and so not chemtrails.

I'd say not quite, but closer. The original

> Any idea except "it's a contrail or non-hidden spraying of some sort"

Meaning the chemtrail conspiracy is "contrails are actually cover ups for chemical spraying that isn't otherwise known", not just "if chemical spraying is covert, then people made a language rule saying it should be referred to as a chemtrail instead".

I.e. chemtrails refers specifically to the conspiracy about a contrail based cover up for covert chemical spraying by world powers, not just a term for a claim that someone somewhere has sprayed chemicals covertly.