Mammoth Uncensored Word List:
51 words ending with st, 16 letters long

accommodationist anesthesiologist anthropomorphist antievolutionist antireductionist archaeozoologist collaborationist confrontationist contrabassoonist controversialist counterculturist counterterrorist cytotechnologist demonstrationist desegregationist electrophysicist environmentalist histopathologist horticulturalist immunogeneticist institutionalist internationalist introspectionist mechanotherapist mycotoxicologist neuropathologist neuroradiologist nonexhibitionist northeasternmost northwesternmost nullificationist otolaryngologist palaeoxylologist paleolimnologist paleoneurologist paleopathologist parapsychologist photogrammetrist phytolithologist phytopathologist premillennialist psychooncologist psychopannychist reincarnationist retrogressionist southeasternmost southwesternmost supranationalist thermodynamicist transcriptionist ultranationalist