thus indicating indefiniteness, THOUSANDS? see Rev. 5:11 and 7:4
Strong G5505
Original Word: χιλι?ς, ?δος, ?
Part of Speech: Noun, Nom. Feminine PLURAL
Transliteration: chilias
Revelation 5:11 I saw, and I heard something like a voice of many angels around the throne, the living creatures, and the elders; and the number of them was ten thousands of ten thousands, and thousands (CHILIAS) of thousands; (WEB KJV WEY ASV BBE DBY WBS YLT NAS RSV NIV)
Revelation 7:4 And I heard the number of those sealed, (144 thousands (CHILIAS) were sealed out of all the tribes of the sons of Israel): (YLT)
http://biblehub.com/topical/t/thousands.htm
Cognate: 5505 xiliás (a feminine noun derived from 5507 /xílioi, "one thousand") - literally, "a thousand"; the cube of 10 (103); also used figuratively to express absolute inclusiveness (complete totality). See 5507 (xilioi).
NAS Word Usage - Total: 22
thousand 20, THOUSANDS 2
http://www.biblestudytools.com/lexicons/greek/nas/chilias.html
In both verses, the word (chilias) being used is feminine PLURAL (THOUSANDS) . This means it is an exceptional usage which does denote a non-literal amount of time.