Definition of one-eighty in English:

one-eighty

noun

US
informal
  • 1A turn to face in the opposite direction.

    ‘I sat in front of them, turning my desk in a one-eighty’
    1. 1.1 A complete reversal in attitude or opinion.
      ‘her personality did a one-eighty and she was back to being sweet and caring’

Origin

1920s: a spelling of 180 degrees.