obtuse

Etymology

marked β is obtuse (sense 1.2) as it is greater than 90° but less than 180°]] From Middle French obtus (“obtuse (geometry); narrow-minded, obtuse; boring, dull, lifeless”), from Latin obtūsus (“blunt, dull; obtuse”), past participle of obtundere, from obtundō (“to batter, beat, strike; to blunt, dull”), from ob- (“prefix meaning against”) (see ob-) + tundō (“to beat, strike; to bruise, crush, pound”) (ultimately from Proto-Indo-European *(s)tewd-, from *(s)tew- (“to hit; to push”)). More at obtund.

adj

1. (now chiefly botany, zoology) Blunt; not sharp, pointed, or acute in form.
   1. (botany, zoology) Blunt, or rounded at the extremity.
      The Herb Pantagruelion hath a little Root somewhat hard and ruff, roundish, terminating in an obtuse and very blunt Point, and having some of its Veins, Strings or Filaments coloured with some spots of white, […] 1653, Francis Rabelais [i.e., François Rabelais], Peter Anthony Motteux, transl.], “How Pantagruel Did Put Himself in a Readiness to Go to Sea; and of the Herb Named Pantagruelion”, in The Works of Mr. Francis Rabelais Doctor in Physick: Containing Five Books of the Lives, Heroick Deeds and Sayings of Gargantua and His Sonne Pantagruel …, volume II, London: Navarre Society, published 1921, →OCLC, book III, pages 57–58
   2. (geometry, specifically, of an angle) Larger than one, and smaller than two right angles, or more than 90° and less than 180°.
      If you put foure Spleets in a Hiue, then cut their backes, where they must leane one against another, to square angles, such as be foure in a circle: if but three, cut them to obtuse angles, such as are three in a circle: (you may readily try them, before you put them in, by Moulds made iust to those formes) and so will they stand close and firme together. 1623, Charles Butler, “Of the Hiues, and the Dressing of Them”, in The Feminine Monarchie: or, The Historie of Bees: Shewing Their Admirable Nature, and Properties, Their Generation, and Colonies, Their Gouernment, Loyaltie, Art, Industrie, Enemies, Warres, Magnanimitie, &c. […], London, →OCLC, chapter 3, section 11, footnote c; republished Mytholmroyd, U.K.: Northern Bee Books, 1985
      More-over, as the Buildings Ambligon / May more receive then Mansions Oxigon / (Because th' acute, and the rect-Angles too, / Stride not so wide as obtuse Angles doe) / So doth the Circle in his Circuit span / More room then any other Figure can. 1641, “The Columnes. The Fourth Part of the Second Day of the II. Weeke”, in Alexander B. Grosart, editor, The Complete Works of Joshua Sylvester: For the First Time Collected and Edited […], Edinburgh Univ. Press, published 1880, lines 198–203, page 156
      Obtuse angles of the through crossing. — The system of the two obtuse-angled points is especially termed the dead-crossing. […] The point itself, less liable to damage than that of the crossing proper, on account of its obtuse form and its position relatively to the wheels, acts the same part towards the tapered portion of the cut rail, as the wing-rail does with respect to the acute-angle of the crossing. 1877, Ch[arles] Couche, “Special Points in the Permanent Way”, in James N. Shoolbred, transl., Permanent Way Rolling Stock and Technical Working of Railways. Followed by an Appendix on Works of Art, volume I, London: Dulau & Co., 37, Soho Square; Paris: Dunod, 49, Quai des Augustins, →OCLC, § XIV (Rail-crossings), paragraph 258, page 316
      If he is standing close beside me I know that our separate axes of vision will meet at an acute angle in the centre of his object, and if we are further apart, at an obtuser angle. 1922, May Sinclair, “Space, Time and Other Consciousnesses”, in The New Idealism, New York, N.Y.: The Macmillan Company, →OCLC, section V, pages 255–256
   3. (geometry, by ellipsis) Obtuse-angled, having an obtuse angle.
      Unless A lies in that part of a semi-infinite strip bounded by AB outside a semi-circle of diameter AB, the triangle is obtuse, so that the probability of getting an obtuse triangle is equal to 1. 2013, Edward J. Barbeau, “Probability and Statistics”, in More Fallacies, Flaws, and Flimflam (Spectrum Series), Washington, D.C.: Mathematical Association of America, page 128
2. Intellectually dull or dim-witted.
   It was a merry time with Carrmen, Watermen, & Porters: for in this Eclipſe, many of them did nothing but drinke, domineere, and ſwagger in Alehouſes; but the often going to and fro of the Pot, made them talke of that, which they had nothing to doe withall, and many times their obtuſe apprehenſions would be medling with the warres betwixt the great Turke and Preſter Iohn, how it was likely to end; […] 1613, [Robert Anton], Moriomachia, imprinted at London: By Simon Stafford, →OCLC, archived from the original on 2018-01-14
   Be you a Remainer or a Leaver, you would have to be particularly obtuse not to see that [Theresa] May's hard Tory Brexit will cost this country and its families more than it can conceivably afford. 27 March 2017, “The Observer view on triggering article 50: As Britain hurtles towards the precipice, truth and democracy are in short supply [editorial]”, in The Observer, London, archived from the original on 2017-08-30
3. Of sound, etc.: deadened, muffled, muted.
   Another addition in Mr. [Joseph Emerson] Worcester's key to the same letter [e] is what he calls the short and obtuse sound, as in her, herd, fern, fervid. Some of these, also, for the sake of indicating the true sound, [John] Walker was obliged to spell with a different vowel. Thus her is directed to be pronounced hur, like u in tub. 1847 January, “Art. VI.—A Universal and Critical Dictionary of the English Language; to which are added Walker’s Key to the Pronunciation of Classical and Scripture Proper Names, much enlarged and improved; and a Pronouncing Vocabulary of Modern Geographical Names. By Joseph E. Worcester. Boston: Wilkins, Carter, & Co. Imperial 8vo. pp. 955. [book review]”, in The North American Review, volume LXIV, number CXXXIV, Boston, Mass.: Published by Otis, Broaders, and Co., No. 154 Washington Street, →OCLC, page 198
4. Indirect or circuitous.
   […] The Conchologist's First Book intends to do something different by describing both the shell and the soft parts of each creature together. The claim seems awfully trivial, I admit, and [Edgar Allan] Poe does press his point only by the obtuse route of stressing an expansion of terminology, from the traditional "conchology" (literally the study of shells, as retained in the title) to "malacology" (or the study of the entire organism—for the animals within the hard shells consist almost entirely of soft parts,[…]). 2003, Stephen Jay Gould, “The Fusions of Unum and the Benefits of Pluribus”, in The Hedghog, the Fox, and the Magister’s Pox: Mending the Gap between Science and the Humanities, New York, N.Y.: Harmony Books; Harvard University Press edition, Cambridge, Mass., London: The Belknap Press of Harvard University Press, 2011, section III (A Saga of Pluribus and Unum: The Power and Meaning of True Consilience), page 185

verb

1. (transitive, obsolete) To dull or reduce an emotion or a physical state.
   The general effect of even a weak infusion of coca leaves is a pleasant irritability and sleeplessness. A stronger infusion keeps hunger away, prevents loss of breath in ascending mountains, dilates the pupil, and obtuses the sensibility to the air. 1861 August, “[Miscellaneous.] Coca”, in The United States Journal of Homœopathy, volume II, New York, N.Y.: C. T. Hurlburt, No. 437 Broome Street, →OCLC, page 549
   [Gustav von] Bunge […] claims that its [alcohol's] primary action is that of a depressant, and that its apparent good effects are simply due to the obtusing influence upon physical and mental suffering. But this is scarcely a correct assumption, as there are individuals in whom the smallest doses produce palpitation of the heart, throbbing of the carotids, and great mental activity. He also claims that alcohol does not produce renewed vigor in tired individuals, but simply obtuses this feeling of exhaustion. 13 July 1900, George M. Kober, “Shall Alcohol be Considered as a Food?”, in Landon B. Edwards, Charles M. Edwards, editors, Virginia Medical Semi-monthly (Richmond), volume V, number 7 (103 overall), Richmond, Va.: J. W. Fergusson & Son, printers [for the Medical Society of Virginia], published 1901, →OCLC, page 205, column 1
   The American avidity for "action" has evidently obtused the perceptions of habitual theatre-goers to all nuances of feeling, and therefore, the harmless romancings of the elderly estranged couple, Mr. and Mrs. Arvik, are interpreted as covering unspeakable iniquities that only exist in the minds of the critics. 1916, Henry Goddard Leach, editor, The American-Scandinavian Review, volume 4, New York, N.Y.: The American-Scandinavian Foundation, →ISSN, →OCLC, page 51