Here's what rhymes with fruitlessness.
rootlessness Words that almost rhyme with fruitlessness
ruthlessness uselessness fruitfulness humourlessness usefulness luminous ruinous mutinous glutinous humanness youthfulness humanise ruefulness glutenous ludicrous voluminous luminance truthfulness uveitis gruesomeness tunefulness lutenists spookiness kookiness humanists ruminants dehumanise scrupulous bituminous albuminous cumulus untruthfulness fumigants illusionists gratuitous lubricants pugilists duelists nutriments unscrupulous contumacious communicants