noun
uselessness, ineffectiveness, fruitlessness, falseness, hollowness, triviality, frivolity, idleness, vanity, emptiness, hopelessness, worthlessness, labor in vain, lost trouble, unprofitableness, purposelessness, pointlessness, meaninglessness, insubstantiality, vainness, bootlessness, falsity, illusion, folly, want of substance, unimportance, carrying water in a sieve, wild-goose chase, sowing the sand, labor of Sisyphus, running around in circles, beating the air, spinning one's wheels, carrying coals to Newcastle.
Antonyms importance*, fruitfulness, significance.
