abstruse

Learned borrowing from Latin abstrūsus (“concealed, hidden; having been concealed”), an adjective use of the perfect passive participle of abstrūdō (“to conceal, hide; to push or thrust away”),[1] from abs- (from ab- (prefix meaning ‘away; from; away from’)) + trūdō (“to push, shove; to thrust”) (ultimately from Proto-Indo-European *trewd- (“to push; to thrust”)).

• (Received Pronunciation) IPA^(key): /əbˈstɹuːs/
• (General American) IPA^(key): /əbˈstɹus/, /æb-/

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• Hyphenation: abs‧truse
• Rhymes: -uːs

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

1. Difficult to comprehend or understand; obscure. [from mid 16th c.]

   Synonyms: abstrusive, arcane, cryptic, esoteric, recondite; see also Thesaurus:incomprehensible

   Antonyms: clear, obvious, understandable; see also Thesaurus:comprehensible

   • [1548], Joanne Hopper [i.e., John Hooper], “Curiositie”, in A Declaration of the Ten Holy Cõmaundementes of Allmygthye God […], [Zurich]: [Christoph Froschauer], →OCLC, page CCXVIII:

     Some time the good makithe an ile end⸝ ãd the ile a godd. In this opiniõ⸝ and in ſcrutable miſterie be werithe all his wittes⸝ and at the end of his cogitacions⸝ fyndithe more abſtruſe⸝ and doutfull obiections thẽ at the beginning⸝ […]

     Sometimes the good maketh an ill end, and the ill a good. In this opinion, and inscrutable mystery be weary all his wits, and at the end of his cogitations, findeth more abstruse, and doubtfull objections than at the beginning, […]

   • 1671, John Milton, “Samson Agonistes, […].”, in Paradise Regain’d. A Poem. In IV Books. To which is Added, Samson Agonistes, London: […] J. M[acock] for John Starkey […], →OCLC, page 65, line 75:

     Be leſs abſtruſe, my riddling days are paſt.

   • 1729, John Machin, “The Laws of the Moon’s Motion According to Gravity”, in Isaac Newton, translated by Andrew Motte, The Mathematical Principles of Natural Philosophy. […] , volume II, London: […] Benjamin Motte, […], →OCLC, page 4:

     Thoſe propoſitions relating to the Moon's motion, which are demonſtrated in the Principia [by Isaac Newton], do generally depend on calculations very intricate and abſtruſe, the truth of which is not eaſily examined, even by thoſe that are moſt skilful; […]

   • 1741, I[saac] Watts, “Of the Sciences, and Their Use in Particular Professions”, in The Improvement of the Mind: Or, A Supplement to the Art of Logick: […], London: […] James Brackstone, […], →OCLC, paragraph I, page 316:

     The beſt VVay to learn any Science, is to begin vvith a regular Syſtem, or a ſhort and plain Scheme of that Science, vvell dravvn up into a narrovv Compaſs, omitting the deeper and more abſtruſe Parts of it, and that alſo under the Conduct and Inſtruction of ſome ſkilful Teacher.

   • 1748, [David Hume], “Essay I. Of the Different Species of Philosophy.”, in Philosophical Essays Concerning Human Understanding, London: […] A[ndrew] Millar, […], →OCLC, page 3:

     'Tis certain, that the eaſy and obvious Philoſophy vvill always, vvith the Generality of Mankind, have the Preference to the accurate and abſtruſe; and by many vvill be recommended, not only as more agreeable, but more uſeful than the other.

   • 1788, Publius [pseudonym; Alexander Hamilton], “Number XXXI. The Same Subject Continued [Concerning Taxation].”, in The Federalist: A Collection of Essays, Written in Favour of the New Constitution, […] , volume I, New York, N.Y.: […] J. and A. M‘Lean, […], →OCLC, page 191:

     The objects of geometrical enquiry are ſo intirely abſracted from thoſe purſuits vvhich ſtir up and put in motion the unruly paſſions of the human heart, that mankind vvithout difficulty adopt not only the more ſimple theorems of the ſcience, but even thoſe abſtruſe paradoxes, vvhich hovvever they may appear ſuſceptible of demonſtration, are at variance vvith the natural conceptions vvhich the mind, vvithout the aid of philoſophy, vvould be led to entertain upon the ſubject.

   • 1831 October 31, Mary W[ollstonecraft] Shelley, chapter IV, in Frankenstein: Or, The Modern Prometheus (Standard Novels; IX), 3rd edition, London: Henry Colburn and Richard Bentley, […], →OCLC, page 36:

     In a thousand ways he smoothed for me the path of knowledge, and made the most abstruse inquiries clear and facile to my apprehension.

   • 1854, Henry Hart Milman, “Pelagianism”, in History of Latin Christianity; […], volume I, London: John Murray, […], →OCLC, book II, page 127:

     A second rescript followed, commanding all bishops not merely to subscribe 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; secret. [late 16th – mid 18th c.]

   Synonyms: (obsolete) abstrused, clandestine, surreptitious; see also Thesaurus:covert, Thesaurus:hidden

   Antonyms: open, patent, unconcealed, unhidden

   • 1612, [Miguel de Cervantes], Thomas Shelton, transl., “Which Speakes of that which after Befell in the Inne; and of Sundry Other Things Worthy to be Knowne”, in The History of the Valorous and Wittie Knight-errant Don-Quixote of the Mancha. […], London: […] William Stansby, for Ed[ward] Blount and W. Barret, →OCLC, part 4, page 500:

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

   • 1648, Joseph Beaumont, “Canto XVII. The Mortification.”, in Psyche: Or Loves Mysterie, […], London: […] George Boddington, […], published 1651, →OCLC, stanza 182, page 328, column 2:

     [T]he abſtruſeſt Things / VVhich in the Mindes dark Temper neſtling ly, / By you expoſed are to every Eye.

   • 1667, John Milton, “Book V”, in Paradise Lost. […], London: […] [Samuel Simmons], […], →OCLC; republished as Paradise Lost in Ten Books: […], London: Basil Montagu Pickering […], 1873, →OCLC, 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; […]

More abstruse and most abstruse are the preferred forms over abstruser and abstrusest. Do not confuse abstruse (hard to understand) with obtuse (failing to understand).

• abstrusely
• abstruseness
• abstrusity
• non-abstruse

• “abstruse”, in The Century Dictionary […], New York, N.Y.: The Century Co., 1911, →OCLC.
• “abstruse”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.
• Philip Babcock Gove (editor), Webster's Third International Dictionary of the English Language, Unabridged (G. & C. Merriam Co., 1976 [1909], →ISBN), page 8
• Laurence Urdang (editor), The Random House College Dictionary (Random House, 1984 [1975], →ISBN), page 7
• Lesley Brown, editor-in-chief, William R. Trumble and Angus Stevenson, editors (2002), “abstruse”, in The Shorter Oxford English Dictionary on Historical Principles, 5th edition, Oxford, New York, N.Y.: Oxford University Press, →ISBN, page 10.

• Staubers, Straubes, surbates, surbeats

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abstruse

1. feminine singular of abstrus

• arbustes

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abstruse

1. inflection of abstrus:
   1. strong/mixed nominative/accusative feminine singular
   2. strong nominative/accusative plural
   3. weak nominative all-gender singular
   4. weak accusative feminine/neuter singular

abstrūse

1. vocative masculine singular of abstrūsus

• “abstruse”, in Charlton T. Lewis and Charles Short (1879) A Latin Dictionary, Oxford: Clarendon Press