Plain rhymes with:
champlain, complain, explain, plane, splain, splaine, ahlen, alain, alaine, alane, alayne, allain, blain, blaine, blane, blayne, champlain, charlayne, complain, delaine, elaine, elane, elayne, explain, galane, helane, lain, laine, lane, layne, ln, maclaine, maclean, mcclain, mcclaine, mcclane, mclain, mclane, plane, slain, slaine, slane, splain, splaine, tulane
Plain sounds like:
pablum, palen, palimony, palin, pallone, palm, palma, palme, paloma, palomino, palomo, palone, paolini, paolino, papillion, papilloma, paulin, paulina, pauline, paulino, paullin, pavilion, pavillion, pelham, pelino, pellman, pellum, pelon, pflaum, pflum, phalen, phelan, philana, philemon, philene, philina, philomena, philon, phylum, pillion, pilon, pipeline, plaino, plam, plamann, plan, plane, plano, playin', plein, plenum, pliny, plohn, plowman, plum, plume, poblano, poehlman, poelman, pohlman, pohlmann, polan, polen, polimeni, polin, polino, pollan, pollen, pollina, pollini, pollinia, pollino, pollman, pollyanna, polonium, poplin, poulin, pullam, pullan, pullano, pullen, pulliam, pullin, pullman, pullum, pylon