Proper rhymes with:
improper, propper, cropper, dropper, gropper, improper, propper, bopper, chopper, clopper, copper, cropper, dropper, gropper, hopper, improper, kopper, opper, popper, propper, shopper, stopper, topor, topper, whopper
Proper sounds like:
periphery, porphyry, prefer, prepare, preparer, proffer, propper, provera, purifier, purveyor