Adjective

(en adjective)

Relating to mystics or mysticism.

Having a spiritual significance that transcends human understanding.

*{{quote-magazine, date=2012-01

, author=Stephen Ledoux , title=Behaviorism at 100 , volume=100, issue=1, page=60 , magazine= citation , passage=Becoming more aware of the progress that scientists have made on behavioral fronts can reduce the risk that other natural scientists will resort to mystical agential accounts when they exceed the limits of their own disciplinary training.}}

Inspiring a sense of spiritual mystery, awe, and fascination.

Adjective

(en-adj)

(obsolete) Concealed or hidden out of the way; secret.

* 1612 , Thomas Shelton (translator), Miguel de Cervantes (Spanish author), The History of the Valorous and Wittie Knight-Errant Don-Quixote of the Mancha , Part 4, Chapter 15, page 500:

O who is he that could carrie newes to our olde father, that thou wert but aliue, although thou wert hidden in the most abstruse dungeons of Barbarie; for his riches, my brothers and mine would fetch thee from thence.

* 1667 , , Paradise Lost :

The eternal eye whose sight discerns abstrusest thoughts.

Difficult to comprehend or understand; recondite; obscure; esoteric.

* 1548 , Bishop John Hooper, A Declaration of the Ten Holy Comaundementes of Almygthye God , Chapter 17 Curiosity, Page 218:

...at the end of his cogitacions, fyndithe more abstruse , and doutfull obiections then at the beginning...

* 1748 , David Hume, Enquiries concerning the human understanding and concerning the principles of moral. London: Oxford University Press, 1973. § 13.

It is certain that the easy and obvious philosophy will always, with the generality of mankind, have the preference above the accurate and abstruse ;

* 1855 , , History of Latin Christianity :

Profound and abstruse topics.