uselessness

noun

1. The condition or quality of being useless or ineffective: bootlessness, fruitlessness, futility, unavailingness, unprofitableness, vainness, vanity. See thrive/fail/exist, used/unused.
2. The condition or state of being incapable of accomplishing or effecting anything: helplessness, impotence, inadequacy, incapability, ineffectiveness, ineffectuality, ineffectualness, inefficacy, powerlessness. See affect/ineffectiveness, strong/weak.

The noun has one meaning:

Meaning #1: the quality of having no practical use
  Synonyms: inutility, unusefulness
  Antonym: usefulness (meaning #1)