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