Definition of misery guts in English:

misery guts

noun

British
informal
  • A person who is constantly gloomy or discontented.

    ‘don't be such a misery guts’
    • ‘Photographs show him looking like an utter misery guts.’
    • ‘He is an absolute misery guts with no apparent sense of humour.’
    • ‘Then you realise that you've become this complete misery guts.’
    • ‘No one likes a misery guts.’
    • ‘I remember promising myself not to be a misery guts about my birthdays as I get older.’