Myriad - History and Usage

History and Usage

A myriad is primarily a singular cardinal number; just as the "thousand" in "four thousand" is singular (one does not write "four thousands people") the word myriad is used in the same way: "there are four myriad people outside". When used as a noun, meaning "a large number", it follows the same rules as that phrase. However, that is not the case originally in Greek, where there is plural.

In English, the term "myriad" is most commonly used to refer to a large number of an unspecified size. In this way "myriad" can be used as either an adjective or a noun. Thus both "there are myriad people outside" and "there is a myriad of people outside" are correct.

Merriam-Webster notes, "Recent criticism of the use of myriad as a noun, both in the plural form myriads and in the phrase a myriad of, seems to reflect a mistaken belief that the word was originally and is still properly only an adjective.... however, the noun is in fact the older form, dating to the 16th century. The noun myriad has appeared in the works of such writers as Milton (plural myriads) and Thoreau (a myriad of), and it continues to occur frequently in reputable English."

Modern Greek still uses the word "myriad" by itself, but also to form the word for million. The word for million is ekatommyrio (hundred myriad — εκατομμύριο); one thousand million is disekatommyrio (twice hundred myriad — δισεκατομμύριο).

The largest number named in Ancient Greek was a myriad myriad and Archimedes of Syracuse used this quantity as the basis for a numeration system of large powers of ten, which he needed to count grains of sand, see The Sand Reckoner.

There is only slight indication that "myria" has at all been used as a metric prefix for 10,000, e.g., 10 kilometres = 1 myriametre. It does not have official status as an SI prefix.

In Sweden and Norway, one mile = 10,000 metres = one myriametre. Before they went metric, one Swedish mile was 10,688 metres and a Norwegian mile was 11,295 metres, so only a small change had to be made to the old mile to make them equal to one myriametre. Even today, both Swedes and Norwegians use the 10,000 metre mile ("mil") to refer to travel distances in everyday language.

In Great Britain, the Ordnance Survey use the term myriad to refer to a 100 km × 100 km area in the National Grid.