the trait of acting stupidly or rashly
"After spending all his savings on a risky startup, he realized that jumping in without research was sheer folly."
a stupid mistake
"Admitting I forgot to water my plants for two weeks was definitely a folly."
the quality of being rash and foolish
"trying to drive through a blizzard is the height of folly"
"adjusting to an insane society is total foolishness"
foolish or senseless behavior
"He realized that quitting his stable job to chase a get-rich-quick scheme was pure folly."
Foolishness that results from a lack of foresight or lack of practicality.
"Building a house on a floodplain without any drainage plan was pure folly."