Here's what rhymes with costac.
back pack stack jack tack tak black attack lack track nach plaque rack sac sack slack hack aback fac knack lac shack smack snack flak mac mak whack wrack yak flack mack wack yack highjack crack quack shellac unpack zodiac clack ipecac claque repack thumbtack skyjack cardiac elegiac hardtack anorak razorback mudpack paperback maniac haversack piggyback crackerjack gunnysack rickrack pickaback counterattack almanac quarterback demoniac lumberjack stickleback amnesiac applejack steeplejack insomniac megalomaniac nymphomaniac Words that almost rhyme with costac
bag tag stag dag flag drag lag rag slag gag hag wag brag fag mag nag sag snag zag shag swag fleabag nosebag blag toerag crag dishrag scrag washrag sleazebag chinwag saddlebag wigwag scalawag scallywag lollygag lallygag bank task tank bask dank talc spank stank basque rank blank thank drank flank mask sank flask frank plank shrank cask franc masque shank hanc lank prank hank yank swank crank clank outrank embank riverbank unmask charabanc antitank databank pointblank