Dumber rhymes with:
dummer, brummer, bummer, comer, drummer, dummer, glummer, hummer, kummer, midsummer, nemir, plumber, plummer, somer, sommer, summar, summer
Dumber sounds like:
dambra, damper, dampier, danbury, denboer, denver, dimambro, dimperio, donapria, donofrio, downpour, dudenhoeffer, dumper, dunbar