Definition of myriads:
(n) :
A countless number or multitude (of specified things)
(adj) :
(modifying a plural noun) Great in number; innumerable, multitudinous
(adj) :
(modifying a singular noun) Multifaceted, having innumerable elements
(n) :
(formal) Ten thousand; 10,000
(n) :
Synonym of decamillennium: a period of 10000 years.