Inanity is complete nonsense. You may be a huge fan of an action movie, but the inanity of its sequel means you're likely to skip the third and fourth installments.
A lot of what passes for comedy on TV is really just inanities: foolish characters in ridiculous situations. And while one political figure makes meaningful speeches that truly inspire you, another tends to spout inanities. An earlier definition of inanity was "emptiness," from a Latin root meaning "empty or useless." During the 18th century, the word came to mean "empty of intelligence, or silly."