Answer: recondite

AnswerCrossword Clue
RECONDITELittle-known
RECONDITEHard to understand.
RECONDITEAbstruse.
RECONDITEObscure.
RECONDITEProfound; abstruse
reconditeconcealed; deep; having to do with something obscure
reconditehidden from sight concealed
reconditedealing with very profound, difficult, or abstruse subject matter.