Cowperthwaite rhymes with:
braithwaite, garthwaite, goldthwaite, actuate, antiquate, braithwaite, counterweight, deadweight, featherweight, fluctuate, garthwaite, goldthwaite, heavyweight, hundredweight, menstruate, middleweight, paperweight, perpetuate, underweight, welterweight
Cowperthwaite sounds like:
cabaret, cafferty, capehart, capriati, capriotti, cavort, chauffeured, chessboard, chevrette, chipboard, cobert, cooperate, cooperated, copperhead, copywrite, copywrited, covered, covert, cupboard, cypert, cyphert, cypriot