Noun foolishness has 3 senses
  1. folly, foolishness, unwiseness - the trait of acting stupidly or rashly
    --1 is a kind of trait
    --1 has particulars:
     indiscretion, injudiciousness; absurdity, fatuity, fatuousness, silliness
  2. folly, foolishness, craziness - the quality of being rash and foolish
    --2 is a kind of stupidity
  3. stupidity, betise, folly, foolishness, imbecility - a stupid mistake
    --3 is a kind of mistake, error, fault