recondite
(of areas of discussion or research) Difficult, obscure.
Difficult to grasp or understand; abstruse, profound.
Little known; esoteric, secret.
(of scholars) Having mastery over one's field, including its esoteric minutiae; learned.
(of writers) Deliberately employing abstruse or esoteric allusions or references; intentionally obscure.
(somewhat archaic) Hidden or removed from view.
(botany, entomology, obsolete, rare, of a structure) Difficult to see, especially because it is hidden by another structure.
(chiefly zoology, rare) Avoiding notice (particularly human notice); having a tendency to hide; shy.
(rare) A hidden or obscure person or thing.
(rare) A scholar or other person who has mastery over his or her field, including its esoteric minutiae.
(obsolete, rare) To conceal, cover up, hide.