Mammoth Uncensored Word List:
27 words ending with rs, 17 letters long

autolithographers autoradiographers bagpiperbagpipers benzyloxycamphors biostratigraphers crystallographers greatgrandmothers intellectualizers lighthousekeepers microcalorimeters micromanipulators microseismometers neurotransmitters numismatographers pachycephalosaurs photointerpreters photopolarimeters photosynthesisers photosynthesizers prediscriminators psychobiographers radiobroadcasters sphygmomanometers superspectaculars transilluminators ultrasonographers videoconferencers