esoteric
abstract
abstruse
academic
arcane
beclouded
blind
buried
cabalistic
cabbalistic
close
clouded
concealed
covered
covert
cryptic
dark
deep
difficult
do up
doctor
eclipsed
enigmatic
erudite
hard
heavy
hermetic
hid
hidden
impenetrable
in a cloud
in a fog
in eclipse
in purdah
in the wings
incommunicado
incomprehensible
inexplicable
latent
learned
mysterious
mystic
mystical
obfuscated
obscure
obscured
occult
opaque
overhaul
astronomical
contradictory
ethnological
inscrutable
intangible
mathematical
metaphorical
metaphysical
mythological
philological
profounder
symbolical
transcendental
unattainable
unexplainable
unfathomable