Here's what rhymes with castaway.
way away weigh whey wei aweigh they may day say pay re lay today j array bay decay gay k ray che hay nay ballet sway fay fe underway yea allay dey hey ley passe rei sei jay kc lei payee rea rj tae zwei bey neigh cay fey hideaway roue shay purvey stowaway play stay delay survey clay essay gray grey obey pray okay prey spray cafe halfway stray tray fray oj slay valet attache bouquet faraway fillet ij ok sleigh waterway bj bk drei fj tj tre underlay bray dray flay getaway parquet soiree belay brae caraway giveaway splay throwaway moray sachet soubriquet toupee flyaway noway trey aurae hurray layaway reweigh spay underpay foldaway tearaway anyway convey yesterday holiday betray dismay repay astray runaway vertebrae defray disarray disobey overlay papillae passageway cabaret dossier francais gangway puree saute alleyway breakaway fistulae sobriquet souffle straightaway carriageway fibulae filet inveigh byplay nisei patellae prepay sorbet takeaway hooray overpay sickbay urethrae briquet medullae outplay outstay umbrae copay copulae display everyday interplay portray cliche lamellae protege sequelae emigre matinee naturae nebulae replay toothache crochet croquet risque scapulae wordplay workaday ricochet airplay pleurae resurvey stingray underplay macrame overplay overstay caesurae uvulae bobsleigh cybercafe misplay walkaway respray formulae naivete societe lingerie maxillae cabriolet roundelay penumbrae communique microarray companionway caravanserais salmonellae tarantulae trabeculae