Myriad (Ancient Greek: μύριος, μυριάδες (myrios, plural myriades), "numberless countless, infinite", is a classical Greek word for the number 10,000. In modern English, the word refers to an unspecified large quantity.

"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 a noun or an adjective.[1] Thus both "there are myriad people outside" and "there is a myriad of people outside" are correct.[2]

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."[2]

The Western numbering system divides large numbers into groups of three digits, and so the names for such numbers follow this division (10,000 = ten thousand). East Asian numbering divides large numbers into groups of four; so in Chinese, Korean, or Japanese, 30,000 really would be "three myriad" (3,0000 - Japanese san-man - Chinese sān wàn (三萬/三万)) - Korean sahm mahn (삼만). One million is a hundred myriad (100 × 10000 instead of 1000 × 1000); the next uniquely named number after a myriad is 億 (Korean eok (억), Chinese pinyin yì, Japanese oku), which is myriad myriad (10000 × 10000) or a hundred million.

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)."


http://en.wikipedia.org/wiki/Myriad