Entry 2 senses Webster, 1913 Abstruse /əb-stro͞os'/ · Ab·struse · IPA /əbˈstɹus/ 01 a. Concealed or hidden out of the way. 1. Concealed or hidden out of the way.[Obs.] “The eternal eye whose sight discerns Abstrusest thoughts.” — Milton. 2. Remote from apprehension; difficult to be comprehended or understood; recondite; as, abstruse learning. “Profound and abstruse topics.” — Milman.