Mammoth Uncensored Word List:
19 words ending with y, 22 letters long

chemicophysiologically chemoheterotrophically chemolithoheterotrophy chemoorganotrophically chemostratigraphically cholecystenterorrhaphy cholecystoduodenostomy cyclostratigraphically electroencephalography electrophysiologically hepatoportoenterostomy hysterotrachelorrhaphy intercomprehensibility lithoheterotrophically lithostratigraphically microspectrophotometry neuropharmacologically photoheterotrophically spectrophotometrically