Abstruse :: Abstruse (a.) Concealed or hidden out of the way.
Abstruse :: Abstruse (a.) Remote from apprehension; difficult to be comprehended or understood; recondite; as, abstruse learning..
Abstruseness :: Abstruseness (n.) The quality of being abstruse; difficulty of apprehension.
Abstrusity :: Abstrusity (n.) Abstruseness; that which is abstruse.