Here's what rhymes with passfail.
fail sale sail veil hail shale vale hale faille male scale mail pale tail tale avail jail nail rail frail gale whale bail stale wail assail bale dale pail snail flail kale topsail taffrail wale trail prevail email travail inhale quail exhale quale braille unveil foresail grail bobtail wassail hightail lugsail detail entail curtail bewail derail mainsail pigtail impale monorail pellmell carrell gunwale ponytail hangnail fingernail countervail martingale swallowtail tattletale nonpareil