Describing someone as a wacko is a derogatory way to say they're quirky or eccentric. It may be tempting to call the neighbor who walks his pet peacock on a leash a wacko, but it wouldn't be very nice.

You'll often hear someone use the word wacko as a way of dismissing people whose opinions or lifestyle they don't understand or agree with. If your cranky uncle complains about the wackos in town, then he's probably talking about a group of people he doesn't like very well. This informal noun first appeared around 1938, from wacky.

Definitions of wacko
  1. noun
    a person who is regarded as eccentric or mad
    synonyms: nutter, whacko
    see moresee less
    type of:
    eccentric, eccentric person, flake, geek, oddball
    a person with an unusual or odd personality
Word Family
F1 image

Express yourself in 25 languages

  • Learn immersively - no memorization required
  • Build skills for real-world conversations
  • Get immediate feedback on your pronunciation
Get started for $7.99/month