Mammoth Uncensored Word List:
39 words ending with in, 13 letters long

bacteriolysin bacteriotoxin canthaxanthin cephalosporin ceruloplasmin chlorocruorin chromoprotein ciprofloxacin corticotropin cycloparaffin digitoxigenin erythropoetin flavopurpurin gonadotrophin hemagglutinin intermountain isoagglutinin lactoglobulin macroglobulin methemoglobin microglobulin nitroglycerin nitroparaffin nucleoprotein overconstrain oxyhemocyanin oxyhemoglobin phthalocyanin phycoerythrin prostaglandin scleroprotein selenoprotein semiporcelain somatotrophin spectinomycin sphingomyelin sporopollenin thyroglobulin transmountain