Great number (6)
(Other definitions for myriad that I've seen before include "Large indefinite number" , "Lots of" , "Host" , "immense quantity" , "Umpteen" .)
(Other definitions for legion that I've seen before include "Host" , "Roman army grouping" , "Body of Roman or French soldiers" , "Part of an army; many" , "Large unit of the old Roman army" .)
(Other definitions for million that I've seen before include "1,000,000" , "Ten thousand hundreds" , "One followed by six zeros" , "A thousand thousnad" , "A thousand thousands" .)
(Other definitions for shedload that I've seen before include "great amount" , "legion" , "Lots - old heads (anag)" , "a lot of it" , "big amount" .)