foolish

UK: ˈfuːlɪʃ | US: ˈfuːlɪʃ

Definition
  1. adj. lacking good sense or judgment; unwise

  2. adj. trivial or silly; not serious

Structure
fool <unwise person>ish <adjective suffix>
Etymology

The word "foolish" derives from the noun "fool," which traces back to Old French "fol" (meaning "madman" or "jester") and Latin "follis" (literally "bellows," metaphorically "windbag" or "empty-headed person"). The suffix "-ish," of Germanic origin, is used to form adjectives indicating a characteristic or quality. Over time, "foolish" evolved to describe behavior resembling that of a fool—lacking wisdom or seriousness.

Examples
  1. It was foolish to go hiking without proper gear in such weather.

  2. She regretted her foolish decision to trust a stranger.

  3. His foolish grin made it clear he wasn’t taking the situation seriously.

  4. The children giggled at the foolish antics of the clown.

  5. Investing all your savings in a risky scheme is simply foolish.