Novus ordo seclorum

The phrase Novus ordo seclorum (, ; "New order of the ages") is the second of two mottos that appear on the reverse (or back side) of the Great Seal of the United States (the first motto is "Annuit cœptis").
Origin and phrase meaning.
The phrase is a reference to the fourth "Eclogue" of Virgil, which contains a passage (lines 5-8) that reads:
The forms "saecla", "saeclorum" etc. were normal alternatives to the more common "saecula" etc. throughout the history of Latin poetry and prose. The form "saeculorum" is impossible in hexameter verse: the "ae" and "o" are long, the "u" short by position.
Medieval Christians read Virgil's poem as a prophecy of the coming of Christ. The Augustan Age, although pre-Christian, was viewed as a golden age preparing the world for the coming of Christ. The great poets of this age were viewed as a source of revelation and light upon the Christian mysteries to come.
The word "seclorum" does not mean "secular", but is the genitive (possessive) plural form of the word "saeculum", meaning (in this context) generation, century, or age. "Saeculum" did come to mean "age, world" in late, Christian Latin, and "secular" is derived from it, through "secularis". However, the adjective "secularis," meaning "worldly," is not equivalent to the genitive plural "seclorum," meaning "of the ages."
The motto "Novus ordo seclorum" was translated by Charles Thomson, a Latin expert who was involved in the design of the Great Seal and proposed it, as "A new order of the ages." He said it was to signify "the beginning of the new American Era" as of the date of the Declaration of Independence.