Here's what rhymes with quarternary.
ordinary marry merry ternary nary very vary fairy urinary bury dairy ferry wary cherry hairy berry sherry tarry canary parry unwary harry legionary tare barre terry faerie wherry arbitrary pulmonary coronary dietary legendary prairie honorary scary luminary remarry buffoonery pessary apiary lapidary elderberry nondairy literary temporary customary missionary capillary dictionary imaginary solitary stationary adversary visionary corollary dysentery mercenary sedentary seminary veterinary emissary itinerary mortuary papillary stationery cautionary centenary aviary bacillary actuary equerry humeri bilberry topiary plagiary necessary military secondary extraordinary monetary commentary hereditary cemetery momentary pituitary reactionary sanitary tributary unitary ancillary budgetary estuary planetary salutary apothecary commissary culinary funerary obituary sanguinary statuary dignitary probationary tutelary beriberi breviary diversionary cassowary dromedary recessionary chokecherry sectary secretary preliminary unnecessary evolutionary monastery sanctuary disciplinary fragmentary involuntary judiciary maxillary pecuniary proprietary inflationary exclusionary fiduciary functionary savagery deflationary epistolary supernumerary unsanitary concessionary huckleberry voluptuary nonliterary tercentenary uncustomary contemporary revolutionary subsidiary vocabulary beneficiary discretionary confectionery expansionary expeditionary genitourinary paramilitary insanitary nonmilitary eleemosynary geostationary bicentenary elocutionary nonhereditary cardiopulmonary interplanetary constabulary undersecretary interdisciplinary multidisciplinary counterrevolutionary Words that almost rhyme with quarternary
belly allele jelly smelly deli telly underbelly vermicelli many messy heavy ready fairly rarely barely semi petty levy penny antennae heady levee medley unfairly jetty teddy bevy faery jenny kepi leggy recce sedgy veggie healthy steady wealthy deadly lengthy gentry unhealthy fleshy carefree sentry sexy sketchy spaghetti sweaty unsteady vestry belfry deathly gayety hefty machete confetti pebbly tempi testy breathy dressy pesky thready lefty wetly already directly especially twenty assembly scarcely elementary gently plenty epilepsy freshly immensely densely frenzy squarely deftly coquetry fleshly stealthy fidgety tensely trendy aplenty baronetcy libretti maidenly marquetry adeptly effendi ineptly friendly correctly complementary intensely intently unfriendly apoplexy halfpenny sullenly hostelry narcolepsy deviancy reassembly preciously woodenly indirectly incorrectly excellency complexly sacredly catalepsy penitently expressly confusedly grotesquely cognoscenti equivalently ambivalently circumspectly