Here's what rhymes with certeinlye.
lie ly rye lye wry lai luy by my high why die dry thy try y buy cry fly guy tie vi hi shy sigh bi bye chi dye fi hy nigh pi pie thai thigh vie dei fry ply psi quae sly ty wir awry hai mai muy nai pry tri trie cy fy kai mei pri sy tai thei wai phi slier apply sky imply nearby rely spy belie decry untie sty bonsai spry amebae stye lanai banzais supply reply thereby deny whereby comply hereby nuclei defy underlie alibi nullify samurai pupae termini amoebae descry mollify overlie aquae deify firefly retry triply blowfly turfy barfly shanghai ripply occupy satisfy stimuli modify multiply alkali verify butterfly certify goodbye notify purify alveoli amplify fortify pacify ratify standby unify lullaby terrify typify dignify edify mortify ramify resupply vilify ossify ultrahigh horrify misapply petrify reunify stupefy overfly scurfy hyperbolae mummify vitrify drachmai gentrify overbuy dandify yuppify identify justify clarify qualify specify classify signify simplify testify glorify gratify diversify magnify rectify beautify falsify solidify codify crucify liquefy oversupply personify acidify dragonfly mystify stratify stultify vivify calcify emulsify revivify cumuli liquify scarify versify prettify beatify refortify speechify syllabify solemnify intensify quantify indemnify demystify electrify preoccupy dissatisfy declassify exemplify disqualify objectify oversimplify detoxify reclassify misidentify transmogrify