Definition of gin and it in English:

gin and it

noun

British
dated, informal
  • A drink of gin and Italian vermouth.

    ‘I can imagine him in a dinner suit, tinkling on a piano, and sipping a gin and it’
    mass noun ‘a glass of gin and it’
    • ‘Two ingredients (three if we count the lemon wedge garnish) comprise the simple gin and it; what could be better than that?’
    • ‘I thought I'd been the perfect hostess till one of the dowagers asked for gin and It.’
    • ‘Elizabeth comes across as a cozy, deeply sympathetic creature with whom you'd love to have tea - or a gin and it - some day.’
    • ‘He never did see much action outside the Pall Mall club, where his restorative gin and it was much appreciated.’
    • ‘The gin and it is a smooth sipper worth getting acquainted with.’

Origin

1930s: it being an abbreviation of Italian (in Italian vermouth).