μυρίος

Etymology
Origin. It may be related to either (as in 'flowing' like the countless waves of the sea) or  (like a countless swarm).

Adjective

 * 1) numberless, countless, infinite
 * 2)  measureless, immense, infinite
 * 3)  endless
 * 4)  much, immensely, incessantly
 * 5)  infinitely
 * 6)  ten thousand, the greatest number expressed in Ancient Greek as a single word

Usage notes
According to the Grammarians (paroxytonic) is the indefinite form, and  (proparoxytonic) is the definite form. However, this distinction is not observed in the manuscripts.