pons as·i·no·rum (p?nz? ?s??-nôr??m)n. A problem that severely tests the ability of an inexperienced person.[New Latin p?ns asin?rum, bridge of fools (nickname of the Fifth Proposition in the Elements of Euclid, due to its difficulty) : Latin p?ns, bridge + Latin asin?rum, genitive pl. of asinus, ass, fool.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.pons asinorum (?æs??n??r?m) n (Mathematics) the geometric proposition that the angles opposite the two equal sides of an isosceles triangle are equal[Latin: bridge of asses, referring originally to the fifth proposition of the first book of Euclid, which was considered difficult for students to learn]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014