Surely rhymes with:
demurely, poorly, prematurely, purely, securely, airlie, arley, arlie, austerely, barely, barley, bierley, bierly, carley, carli, carly, cavalierly, charley, charlie, clearly, corley, darley, dearly, decarli, demurely, fairley, fairlie, fairly, farley, farly, gnarly, gorley, gourley, harley, hourly, kalgoorlie, marley, mccarley, mcsorley, merely, morley, myrlie, narly, nearly, orly, parley, poorly, prematurely, purely, rarely, sarli, securely, severely, sincerely, sorely, sorlie, squarely, storlie, thorley, torley, unfairly, varley, warley, wehrli, wehrly, whorley, yearly
Surely sounds like:
sara-lee, sarli, sarlo, scarola, scharlau, schierl, schroll, scrawl, scroll, searl, searle, securely, serial, serle, serlo, sharell, sharla, sharlow, sharyl, sherley, sherrell, sherrill, sheryl, shirell, shirelle, shirl, shirlee, shirley, shirlie, shirrell, showgirl, shrill, shurley, sorel, sorell, sorely, sorlie, sorrel, sorrell, sourrouille, squarely, squirrel, surly, surreal, surrell, swirl