Here's what rhymes with costly.
Words that almost rhyme with costly
softly courtly partly shortly calmly awfully godly hotly oddly coarsely motley portly arty collie crossly tartly party army coffee copy forty folly quasi barley faulty hearty warmly wrongly darkly falsely glossy harshly haughty jolly nobly poly sorely volley frosty gaudy khaki mossy naughty orgy parsley posse salty smartly carpi cocky gory hoarsely holly jaunty knotty parley saucy sortie archly bossy cockney corny dolly doughty fourthly karate potty warty body hardly largely glory sharply sorry broadly lofty promptly rocky hardy larvae lobby donkey fondly hobby palsy quarry sparsely foggy hoary hockey horny lordly lorry marshy poppy tardy tawny thorny trolley ungodly armoury balmy bawdy bonny chalky colliery jockey sari shoddy soggy starkly tarsi tawdry baldly boggy bonnie chary choppy dory groggy mammy mommy palmy spotty talkie toddy zombie story strongly laundry proxy stormy storey bronchi epoxy floppy paltry sloppy starry swampy swarthy brawny dropsy frothy starchy staunchly stocky thrombi chicory scrawny vulgarly hierarchy allegory embody oligarchy literati commonalty pylori safari divorcee salami category auditory melancholy uniformly oratory photocopy purgatory nonchalantly personalty tsunami amatory integrally nugatory territory everybody antibody orthodoxy migratory patriarchy secretory derogatory repertory signatory dilatory gustatory laudatory lavatory multiparty pianoforte rotatory matriarchy vainglory laboratory inventory statutory mandatory obligatory dormitory predatory desultory excretory oscillatory promissory dedicatory prefatory vibratory accusatory expiatory heterodoxy hortatory respiratory regulatory inhibitory circulatory promontory repository transitory depository observatory streptococci declaratory defamatory expository initiatory staphylococci commendatory consolatory declamatory deprecatory subcategory suppository explanatory inflammatory preparatory ambulatory compensatory conciliatory exploratory retaliatory celebratory prohibitory reformatory condemnatory ejaculatory interrogatory contributory anticipatory hallucinatory interlocutory investigatory propitiatory discriminatory participatory congratulatory nondiscriminatory