Antonyms for Clearness (opposite meaning)
WordNet sense 1 (incomprehensibility as a result of not being clear):
unclearnessWordNet sense 2 (the quality of being unclear or abstruse and hard to understand):
obscurityWordNet sense 3 (the quality of being opaque to a degree; the degree to which something reduces the passage of light):
opacityFrom the ODE community, based on WordNetadd/edit