Definition of bats in English:

bats

adjective

dated, informal
  • [predicative] (of a person) crazy; insane.

    • ‘But he was bats and incomprehensible before he took ill.’
    • ‘I think the kid and I knew she was bats but she was a hoot to be with.’
    • ‘She was bats and contrary, but she seemed to be self-aware and have a genuine sense of humour about her own battiness and contrariness.’
    • ‘Either that, or she was bats.’
    • ‘He was bats for buying in the face of a housing downturn.’
    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/