recondite
adj. C2 Proficiency Oxford US //ˈɹɛkənˌdaɪt// UK //ɹˌiːkəndˈaɪt// re·con·dite
adj. describing something that is difficult to understand because it is about a very specialized subject. You use this for topics that only a few experts know well.
adj. dealing with very specific or hidden knowledge that is beyond ordinary understanding; obscure or abstruse. Adjective, formal register.
The professor studies recondite subjects that few people understand.
The researcher spent decades investigating recondite aspects of ancient history that most scholars had entirely ignored.
The essay provides a fascinating glimpse into recondite areas of theoretical physics, though its dense terminology often proves impenetrable to those without a background in advanced mathematics.