The origin of some words is a complete mystery — even for the world’s best lexicographers. A friend was wondering why guinea pigs are so called: they don’t come from Guinea and they are not pigs. This is one of the many words whose origin is just a maze of theories.

One theory is that the word is a corruption of Guyana, on the south-east coast of South America. But the guinea pig comes from the Andes.

Some have speculated that they were brought to Europe by way of Guinea, so some people believed they came from Africa. The English at one time used ‘Guinea’ to refer to any faraway country, so some think the animal’s name is simply an indication of its foreignness.

The common theory that they were sold for a guinea is sheer nonsense: the guinea coin was first struck in England in 1663 and the term ‘ginny-pig’ was recorded as early as 1653.

Some lexicographers have suggested guinea could be an alteration of ‘coney’ because guinea pigs were referred to as ‘pig coneys’ in Edward Topsell’s 1607 treatise on quadrupeds.

The English weren’t the only ones to give this animal a porcine link. They are called ‘Meerschweinchen’ in German and in Polish they are ‘swinka morska’, both words meaning little sea pigs.

The French call them ‘cochon d’Inde' (Indian pig) and in Portuguese they are sometimes called ‘porquinho da India’ (also Indian pig).

However, the Spanish get away from the porcine connection and refer to it as ‘conejillo de Indias’ (little rabbit of India).

The ‘sea pig’ reference in German and Polish helps to explain why they were called pigs. Centuries ago, sailing ships taking on provisions in South America stocked up with guinea pigs. They could survive for long periods in cramped quarters reminiscent of pig pens, so they were a convenient source of fresh meat.

In the late 18th and early 19th centuries, a ‘guinea pig’ was a term of reproach. Tobias Smollet wrote: “A good seaman he is…none of your guinea pigs.”

In the 19th century a guinea pig could also be anyone whose fee was one guinea — vets, doctors or special jurymen. There was also another kind of guinea pig: a public company director who attended board meetings just to collect his fee.

From 1939 to 1945, a guinea pig was an evacuated civil servant, especially BBC personnel to whom the government paid one guinea a week towards their board and lodging.

The term was applied in 1930 to anyone on whom experiments were carried out and also to those who took part in trial runs of new products. Guinea pigs had earlier been used in medical experiments in labs and hospitals.

A ‘guinea hen’ was an early name for turkey, especially a female. Shakespeare used ‘guinea hen’ to mean a prostitute or a courtesan.

The British gold coin known as a guinea was so named because it was made of gold from Guinea, on the west coast of Africa. It had a nominal value of one pound when first struck in 1663 for trade with Africa.

It became legal tender in Britain from 1717 when its value was fixed at 21 shillings. The term is no longer used except for some professional fees, the prize for some horse races and the prices of goods sold at auction.

And until at least the mid-20th century, the BBC paid its contributors in guineas. This led to the term ‘worth a guinea a minute’, used for a comedy team with a good line in repartee.

In street markets and secondhand shops in the 1920s, the term ‘worth a guinea a box’ was used to describe any cheap but useful small item. The phrase was borrowed from the much earlier advertising slogan for Beecham’s Pills.

In the 18th century, the term ‘Guinea-gold’ meant sincere or utterly dependable. Gold from Guinea was said to be of a ‘magnificent yellow’. The 19th century simile ‘yellow as a guinea’ was used for anything of a rich yellow.

The term ‘it’s a guinea to a gooseberry’ was late 19th century sporting slang for long odds. A variation on this theme was ‘a guinea to a goose’. But in the City they preferred to say ‘Lombard Street to a China orange.’

Humans are so complex and different from each other that generalisations applied to them are frequently way off the mark. It is said that ‘Essex girls’ are supposed to be unintelligent, materialistic and with no taste. But the three women from Essex whom I know have none of these traits.

The term ‘Essex man’ also exists, but as I don’t know any men from Essex, I have no way of knowing if it is accurate in any way. But at least we do know who coined ‘Essex man’.

It was journalist Simon Heffer in an article in the Sunday Telegraph on October 7, 1990. But unlike the term ‘Essex girl’, which is completely disparaging, an ‘Essex man’ has worthy qualities.

Heffer said an ‘Essex man’ was likely to be ‘mildly brutish and culturally barren', but he is patriotic and values family life. He added that ‘Essex man’ is decent enough, after drinking in City bars, to be sick before boarding the train home from Liverpool Street station.

A friend wanted to know how and when the ‘Great’ got into Great Britain. When the Romans conquered a bit of the country they called it Britannia. But the French preferred to say ‘Grande Bretagne’ to distinguish it from Bretagne, or Brittany. It is thought that Great Britain is a simple translation of this following the Norman Conquest in 1066.

Although there is a reference to ‘Bretayne the grete’ in a 14th century chronicle, the first official use of ‘Great Britain’ was in 1604 when James VI of Scotland became James I of Great Britain.

The 1707 Act of Union formalised the name, merging the kingdoms of Scotland and England into the kingdom of Great Britain.