Arcane (8)
'arcane' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for esoteric that I've seen before include "Mystic" , "Secret, mysterious" , "Support jutting out from wall" , "Secret; taught to few" , "Cryptic" .)
'arcane' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for abstruse that I've seen before include "Hard to understand, complicated" , "Difficult to penetrate or understand" , "Hard to understand, recondite" , "Difficult to understand, obscure" , "Hard to understand, perhaps profound" .)
'arcane' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for mystical that I've seen before include "of occult rites" , "Inexplicable" , "Having a spiritual significance" , "Occult, spiritual" , "Sacredly obscure" .)