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