What is it about days and colours that makes them such happy pairs? Journalists, marketers, idealists, they all love to give the days of the week a dab of paint: just google for Black Monday, Yellow Tuesday, Red Wednesday and Green or Purple Friday, and you’ll find all sorts of catastrophes, sales campaigns, football matches, environmental activism and gay solidarity.

Most of these are recent inventions, but others have long become household terms, in English or other languages. Here’s an incomplete list – feel free to add.

Blue Monday
Long before becoming a popular meme for a day in late January, claimed to be the gloomiest of the year, ‘blue Monday’ was already a well-known idiom in Dutch: blauwe maandag. Somebody who read philosophy ‘for a blue Monday’ studied it for a very short period and unsuccessfully. As for why a Monday and why blue, nobody is sure, though theories abound.

White Tuesday
The Tuesday just before Lent has many names: Shrove Tuesday in English (related to shrive for ‘confess’), Fastnacht (Lent Eve) in German, and mardi gras (fat Tuesday) in French. Swedish has two names for it: fettisdagen (again, fat Tuesday), and vita tisdagen or ‘white Tuesday’, so named after the while flour used for the celebratory buns.

Red Wednesday
Days of the week called red usually refer to historical events that are either bloody or of a communist nature, or both. Not so the Iranian ‘red Wednesday’ or Chaharshanbe Suri. It is the name of a celebration on the last Tuesday (!) night before New Year’s Eve, which in Iran is on or around 21 March. (This happens to coincide with International Colour Day.)

Multicoloured Thursday
Nowhere is Thursday really called that, but Maundy Thursday, three days before Easter, must be the most colourful day of the year, at least in its name. In German, Czech and Slovak, it’s considered green (Gründonnerstag, zelený čtvrtek, zelený štvrtok). Speakers of Dutch prefer to view it as white (witte donderdag). But the language that turns Maundy Thursday into gaudy Thursday is Swedish, which prefers it pink: skärtorsdagen. This is really an accident of linguistic history: back when the name was given, skär meant ‘clean’ or ‘bright’.

Black Friday
This is one of the more apt but less common names for Good Friday, the day commemorating Jesus’ crucifixion. Outside the religious domain, days are called ‘black’ when they are perceived to be highly unpleasant. In the United States, the day after Thanksgiving (fourth Thursday of November) has for half a century been labelled Black Friday. It marks the beginning of the Christmas shopping season and is characterised by crowded shops, heavy traffic and similar horrors of horde behaviour. ‘First World problems’ sums it up neatly.

Black Saturday
First World problems are not exclusively American. Each summer, France suffers one or more samedis noirs (black Saturdays), when the north of the country en masse starts heading south on the very same morning. Millions of Peugeots, Renaults and Citroëns will clog all the main arteries, especially the Autoroutes du Soleil or Motorways of the Sun.
In the old days before shopping malls and motorways, people had other, equally pressing worries, such as the secret meetings of evil witches. One of the names for these was ‘black Sabbat(h)’, based on the Hebrew word for Saturday. Nonetheless, these meetings were not thought to be held on any particular day of the week, but rather on certain dates.

White Sunday
Pentecost, the fiftieth day after Easter, was known to the Anglo-Saxons as ‘white Sunday’ (hwita Sunnandæg). The word lives on as Whitsunday.

The whole rainbow
To find a week that is entirely like a rainbow, head for Southeast Asia. In Thai and Khmer culture, every day has its own colour (except Wednesday, which has two). Rather than speak of ‘yellow Monday’, it makes more sense to say that ‘the Monday is yellow’. The others are as follows: Tuesday pink, Wednesday green (with the evening a lighter green), Thursday is orange, Friday blue, Saturday purple and Sunday red.

I’m sure there are many more well-established ‘colour days’ in other languages. Yellow Tuesdays in Greek, perhaps, or turquoise Fridays in Finnish? Do let us know!