Mammoth Uncensored Word List:
62 words ending with ls, 14 letters long

anterolaterals antibacterials antidiarrheals antimicrobials antiprotozoals attobecquerels biconditionals clinodiagonals cockerspaniels cosmeceuticals cybercriminals decabecquerels decibecquerels dinitrophenols dolichocephals duotrigesimals gigabecquerels gynecologicals hexavigesimals infinitesimals internationals isogeothermals isoproterenols kilobecquerels macrodiagonals mangoldwurzels megabecquerels multinationals nanobecquerels neurochemicals noncommercials nonhomosexuals nonreciprocals nutraceuticals orthodiagonals pentabarbitals pentobarbitals perissodactyls petabecquerels petrochemicals phenobarbitals phytochemicals picobecquerels quadrilaterals quadriliterals quindecennials schutzstaffels seminocturnals semiochemicals steeringwheels supercriminals superregionals tablespoonfuls terabecquerels tercentennials thundersqualls tortoiseshells tricentennials unnonagesimals unsexagesimals ventrolaterals xiphiplastrals