Definition of bats in English:

bats

adjective

informal, dated
  • [predicative] (of a person) mad.

    • ‘I know she's good at getting press (partially because she's really good at marketing her fair-weather femininity), but it's obvious that she's bats.’
    • ‘I have in fact stated a number or times that I think he's bats.’
    • ‘We realize in short order that she's bats, and that simple observation steals a great deal of power from the proceedings.’
    severely mentally ill, mentally ill, insane, mad, certifiable, deranged, demented, of unsound mind, out of one's mind, not in one's right mind, not together, crazed, maniac, maniacal, lunatic, unbalanced, unhinged, unstable, disturbed, distracted, stark mad, manic, frenzied, raving, distraught, frantic, hysterical, delirious, mad as a hatter, mad as a march hare
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Origin

Early 20th century: from the phrase have bats in the belfry (see bat).

Pronunciation:

bats

/bats/