Mammoth Uncensored Word List:
22 words ending with sh, 12 letters long

antibacklash buccaneerish clothesbrush dilettantish disembellish disestablish dissenterish electroclash gazetteerish midsummerish overflourish pollyannaish preestablish schoolboyish shavingbrush squirrelfish superstylish sycophantish synchroflash thunderflash uncoquettish undernourish