recondite
Concise Oxford English Dictionary © 2008 Oxford University Press:
recondite /ˈrɛk(ə)ndʌɪt, rɪˈkɒn-/
▶adjective (of a subject or knowledge) obscure.
– origin C17: from L. reconditus ‘hidden, put away’, past part. of recondere, from re- ‘back’ + condere ‘put together, secrete’.
'recondite' also found in these Oxford entries:

