深奥

深奧
shēnào
  1. profound
  2. abstruse
  3. recondite
  4. profoundly

CEDICT

Entry Composition

=1 深 shēn old variant of 深 shēn
=1 深 shēn deep (lit. and fig.)
2 奥 ào
  1. obscure
  2. mysterious