Definition of blue Monday in English:

blue Monday

noun

informal
  • 1A Monday on which one feels gloomy or dispirited, especially because one has to return to work after the weekend:

    ‘remember that when you're having a blue Monday, just climbing out of bed is a positive start’
    • ‘It was another blue Monday for investors, with the share dropping 5% in early morning trade.’
    • ‘Four plates we wanted to try were eighty-sixed; clearly it was definitely a blue Monday.’
    • ‘Between us we have written about almost every continent, hiked many a trail, sailed a few seas—and also wrestled with canceled flights and occasionally weathered blue Mondays.’
    • ‘They experienced a blue Monday as investors sent the stock plunging by close to 30% in midday trade.’
    • ‘It's Monday, perhaps a blue Monday at the start of the week, so maybe you all need cheering up a bit.’
    • ‘The evening before they dined out on fine Italian cuisine to alleviate any worries of a blue Monday.’
    • ‘Monday, blue Monday, came as it must.’
    • ‘It was a blue Monday for the company when a newspaper printed five suggestions why consumers shouldn't buy its upcoming console.’
    • ‘It's a blue Monday and the weekend had not been so good either because the golf course was flooded.’
    • ‘For him, tomorrow will be a particularly blue Monday; his firm scrapped a €200 million flotation that would have valued him at €80 million.’
    1. 1.1British (in the northern hemisphere) a Monday in January, typically the third Monday of the month, that is characterized as the most depressing day of the year:
      ‘snow and ice brought travel chaos across the UK on Blue Monday’
      • ‘A wide shot of the polar ices or ideas on how to brighten your Blue Monday might not change your life but there's very clearly a good amount of not too intrusive content on the page to greet you.’
      • ‘Since the idea of Blue Monday has become well known he has admitted the idea of a single most depressing day was 'not particularly helpful' because it became 'a self-fulfilling prophecy'.’
      • ‘There's no better way to banish the January blues than by instantly lifting the spirits with a feel-good movie and even Blue Monday is no match for our mood boosting top 10.’
      • ‘For those struggling with Blue Monday, tips for getting through it include capitalising on nature by making sure to spend as much time outside as possible and doing exercise.’
      • ‘The mist appeared in Derbyshire on 'Blue Monday'.’
      • ‘According to commentators, Blue Monday leaves its sufferers feeling down or, in some cases, depressed.’
      • ‘Tomorrow is Blue Monday—when gloomy weather, post-Christmas bills, and failure of our New Year resolutions are said to make us the most miserable we'll feel all year.’
      • ‘Several publications offer tips to emerge from Blue Monday—as it's been dubbed—with a smile.’
      • ‘January 18 was officially Blue Monday, when huge swathes of the population are said to be suffering from depression after Christmas excesses, debts, going back to work, and miserable weather.’
      • ‘As it's Blue Monday, why not pass this on to someone to cheer them up.’
      • ‘After a weekend of sad and troubling news, Plymouth is waking up today to a very wet and windy Blue Monday.’

Origin

Late 18th century: originally in German contexts, in reference to a Monday during which people chose not to work, especially as a result of excessive indulgence over the course of the weekend (the reason why such a Monday should be described as blue is not clear). The modern meanings derive from blue in the sense ‘melancholy, sad, or depressed’ (see blue.