1. Hidden from sight: concealed.
2. Difficult or impossible for one of ordinary understanding or knowledge to comprehend: deep.
3: of, relating to, or dealing with something little known or obscure.
– reconditely, adverb.
– reconditeness, noun.
[Origin: Latin reconditus, past participle of recondere to conceal, from re– + condere to store up, from com– + –dere to put.]
“The Anarchist Cookbook, with its dangerously flawed bomb formulae, hasn’t maimed half so many hands as HPL’s mythos. His writings look more like fiction than allegorically-described recipes to most people, which is a good thing; but every so often a reader of his more recondite works becomes unhealthily obsessed with the idea of the starry wisdom behind it, starts thinking of it as something real, and then tries to reverse-engineer the design of the pipe bomb he’s describing, not realizing that Quality Control was not his strong point. – Equoid, Charles Stross.