Abstruse \Ab*struse"\, a. [L. abstrusus, p. p. of abstrudere to
   thrust away, conceal; ab, abs + trudere to thrust; cf. F.
   abstrus. See {Threat}.]
   1. Concealed or hidden out of the way. [Obs.]
      
[1913 Webster]


            The eternal eye whose sight discerns
            Abstrusest thoughts.                  --Milton.
      
[1913 Webster]


   2. Remote from apprehension; difficult to be comprehended or
      understood; recondite; as, abstruse learning.
      
[1913 Webster]


            Profound and abstruse topics.         --Milman.
      
[1913 Webster]

abstruse
     adj : difficult to penetrate; incomprehensible to one of ordinary
           understanding or knowledge; "the professor's lectures
           were so abstruse that students tended to avoid them";
           "a deep metaphysical theory"; "some recondite problem
           in historiography" [syn: {deep}, {recondite}]

102 Moby Thesaurus words for "abstruse":
   Herculean, abstract, arcane, arduous, beclouded, blind, brutal,
   buried, civilized, close, clouded, complex, complicated, concealed,
   covered, covert, critical, cultivated, cultured, deep, delicate,
   demanding, difficile, difficult, eclipsed, educated, encyclopedic,
   erudite, esoteric, exacting, formidable, hairy, hard, hard-earned,
   hard-fought, heavy, hermetic, hid, hidden, hypothetical, ideal,
   in a cloud, in a fog, in eclipse, in purdah, in the wings,
   incommunicado, intricate, jawbreaking, knotted, knotty, laborious,
   latent, learned, lettered, literate, mean, mysterious, no picnic,
   not easy, obfuscated, obscure, obscured, occult, operose,
   pansophic, polyhistoric, polymath, polymathic, profound, recondite,
   rigorous, rough, rugged, scholarly, scholastic, secluded, secluse,
   secret, sequestered, set with thorns, severe, spiny, steep,
   strenuous, studious, thorny, ticklish, toilsome, tough,
   transcendental, tricky, under an eclipse, under cover,
   under house arrest, under wraps, underground, unknown, uphill,
   wicked, wise, wrapped in clouds