Mammoth Uncensored Word List:
40 words ending with rs, 16 letters long

autotransformers chromatographers chronobarometers cigaretteholders cinematographers circumnavigators copyrightholders counterattackers counterreformers crossclassifiers crosspollinators crossquestioners diastereoisomers extracurriculars historiographers immunomodulators malpractitioners mechanoreceptors microphotometers microprogrammers misunderstanders nonphotographers overneutralizers phacoemulsifiers photomultipliers photosensitisers photosensitizers phototransistors phototypesetters phytogeographers prestidigitators radiogoniometers subcommissioners supersensitisers telethermometers thermoregulators transmissometers ultramarathoners vasoconstrictors weatherstrippers