recondite

Short definition from Wiktionary

Adjective

1. 1
   Difficult, obscure: Difficult to grasp or understand; abstruse, profound.
2. 2
   Difficult, obscure: Little known; esoteric, secret.
3. 3
   Difficult, obscure: Having mastery over one's field, including its esoteric minutiae; learned.
4. 4
   Difficult, obscure: Deliberately employing abstruse or esoteric allusions or references; intentionally obscure.
5. 5
   Hidden or removed from view.
6. 6
   Hidden or removed from view: Difficult to see, especially because it is hidden by another structure.
7. 7
   Hidden or removed from view: Avoiding notice (particularly human notice); having a tendency to hide; shy.

Noun

1. 1
   A recondite (hidden or obscure) person or thing.
2. 2
   A scholar or other person who is recondite, that is, who has mastery over his or her field, including its esoteric minutiae.

Verb

1. 1
   To conceal, cover up, hide.