• (adv.) In an abstruse manner.
Ab·struse'ly adverb In an abstruse manner. 
[adv] - in a manner difficult to understand
abstrusely 1. In a manner difficult to understand. 2. In a concealed; hence, remote from apprehension. 3. Difficult to be comprehended or understood; opposed to what is obvious.
adverb in a manner difficult to understand; `the professor`s abstrusely reasoned theories were wasted on his students`