@Moon @rasterman @djsumdog @olmitch again, at the time, so called "gnostics" would not have called themselves "gnostics."
The term comes from Gnosis, which might be best translated from the Greek as "experiential knowledge" or more generically esoteric knowledge.
https://www.etymonline.com/word/Gnosis
I've never heard it used specifically as a term of abuse anywhere, but would love to see an example.