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From French abstrus[1] or its source, Latin abstrūsus (hidden, concealed), the perfect passive participle of abstrūdō (conceal, to push away)[2], itself from ab, abs (away) + trūdō (thrust, push).[3] Cognate with German abstrus.



abstruse (comparative abstruser or more abstruse, superlative abstrusest or most abstruse)

  1. Difficult to comprehend or understand. [First attested in the late 16th century.][1]
    Synonyms: recondite, obscure, esoteric
    • 1548, Bishop John Hooper, “Curiosity”, in A Declaration of the Ten Holy Comaundementes of Almygthye God, page 218:
      [] at the end of his cogitacions / fyndithe more abſtruſe, and doutfull obiections thē at the beginning []
    • 1748, David Hume, “An Enquiry concerning Human Understanding”, in Essays and Treatises on Several Subjects[1], volume II, new edition, London: T. Cadell, published 1772, section I, page 4:
      It is certain that the eaſy and obvious philoſophy will always, with the generality of mankind, have the preference above the accurate and abſtruſe ; and by many will be recommended, not only as more agreeable, but more uſeful than the other.
    • 1854, Henry Hart Milman, “Pelagianism”, in History of Latin Christianity, volume I, London: John Murray, book II:
      A second rescript followed, commanding all bishops not merely to subscribe to the dominant opinions on these profound and abstruse topics, but to condemn their authors, Pelagius and Cœlestius, as irreclaimable heretics, and this under pain of deprivation and banishment.
  2. (obsolete) Concealed or hidden out of the way; secret. [Attested from the late 16th century until the mid 18th century.][1]
    • 1612, Thomas Shelton, transl., chapter XV, in The History of the Valorous and Wittie Knight-Errant Don-Quixote Of the Mancha[2], London: William Stansby for Ed[ward] Blount, translation of original by Miguel de Cervantes, part 4, 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, John Milton, “Book V”, in Paradise Lost. A Poem Written in Ten Books, London: Printed [by Samuel Simmons], and are to be sold by Peter Parker [] [a]nd by Robert Boulter [] [a]nd Matthias Walker, [], OCLC 228722708; republished as Paradise Lost in Ten Books: The Text Exactly Reproduced from the First Edition of 1667: [], London: Basil Montagu Pickering [], 1873, OCLC 230729554, lines 709–714:
      [] Mean while th’ Eternal eye, whoſe ſight diſcernes / Abſtruſeſt thoughts, from forth his holy Mount / And from within the golden Lamps that burne / Nightly before him, ſaw without their light / Rebellion riſing, ſaw in whom, how ſpred / Among the ſons of Morn, what multitudes / Were banded to oppoſe his high Decree []

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  1. 1.0 1.1 1.2 “abstruse” in Lesley Brown, editor-in-chief; William R. Trumble and Angus Stevenson, editors, The Shorter Oxford English Dictionary on Historical Principles, 5th edition, Oxford; New York, N.Y.: Oxford University Press, 2002, →ISBN, page 10.
  2. ^ Philip Babcock Gove (editor), Webster's Third International Dictionary of the English Language, Unabridged (G. & C. Merriam Co., 1976 [1909], →ISBN), page 8
  3. ^ Laurence Urdang (editor), The Random House College Dictionary (Random House, 1984 [1975], →ISBN), page 7

Further readingEdit





  1. feminine singular of abstrus






  1. vocative masculine singular of abstrūsus