Someone who is ‘yellow-bellied’ is said to be cowardly or extremely timid, and to be ‘in the red’ usually means to be in debt or owe someone money.

In 1914, the Order of the White Feather was founded with the aim of shaming men into enlisting in the army by encouraging women to present white feathers to men, not in uniform. The white feather has since become a symbol of cowardice.

The first version of the term is seen in The Merchant of Venice, written between 1596-1599, where Shakespeare wrote the phrase ‘green-eyed jealousy’. Later, in Othello (1604), Shakespeare writes “O! beware, my lord, of jealousy; it is the green-eyed monster which doth mocks the meat it feeds on.” This line is thought to refer to cats (which are often green-eyed) who tease mice before they kill them.

Workers are sometimes categorised by the colour of collar they typically or historically wore to work. Blue-collar workers generally perform manual work in industries such as construction, technical installation, maintenance among other things. While the term white-collar worker tends to be used to describe people who perform managerial or administrative work in an office setting.

You would say that someone has blue blood if they come from a family that has a high social rank. It is a literal translation of the Spanish phrase 'sangre azul' and is thought to have originated from the blueness of the veins of people with a pale complexion, compared to those with darker skin. Tanned skin was usually an indicator of people who undertake labour outside, so higher classes would be paler from staying out of the sun.

Sacred white elephants were kept by monarchs in Southeast Asia. They were symbols of prosperity but because they were sacred, laws protected them from labour. This meant they were costly to keep and difficult to give away, and couldn’t be put to much practical use.

The term ‘tickling’ has been used in relation to pleasure and dating since the 17th century. It’s thought that the extension to ‘tickled pink’ comes from the idea that great enjoyment might make someone glow with pleasure.

Violets are known as reclusive and understated flowers because they grow near to the ground. They are quite small, fragile, and their flowers are often hidden in their leaves and by bigger plants nearby. The phrase ‘shrinking violet’ was originally used to describe the flower and was first used to describe a person in an American newspaper.