Mammoth Uncensored Word List:
30 words ending with se, 15 letters long

apophthegmatise comprehensivise contraclockwise conventionalise counterresponse deindustrialise departmentalise endoglycosidase enteropeptidase experimentalise galactopyranose governmentalise hexoseaminidase intellectualise methylcellulose metropolitanise mischaracterise overrationalise photosynthesise presbyterianise professionalise prototelomerase reconceptualise recontextualise reindustrialise resurrectionise supernaturalise totalitarianise undercapitalise unprotestantise