NOUN: Inflected forms: pl. gen·e·ses (-sēz')
1. The coming into being of something; the origin. See synonyms at beginning. 2. Genesis abbr. Gen. or Gn See table at Bible.
ETYMOLOGY: Latin, from Greek. See genə- in Appendix I.
The American Heritage® Dictionary of the English Language, Fourth Edition. Copyright © 2000 by Houghton Mifflin Company. Published by the Houghton Mifflin Company. All rights reserved.
Quoting from The Map That Changed the World: William Smith and the Birth of Modern Geology by Simon Winchester:
It was left to the genial Irish prelate James Ussher, while he was bishop of Armagh, to fix the date [of Creation] with absolute precision. According to his workings, which he managed to convince his clerical colleagues were impeccably accurate, God had created the world and all its creatures in one swift and uninterrupted process of divine mechanics that began on the dot of the all-too-decent hour of 9 A.M., on a Monday, October 23, 4004 B.C.
Before that is another paragraph. Since I've never seen one of those older Bibles, I didn't know about this:
Lest anyone forget, all the Bibles that were in use at the time [of William Smith's birth] had dates printed in bold scarlet letters in the margins, annotations to the verses of the Old Testament, designed to act as a gentle reminder. "In the Beginning, God . . . " had the number "4004 B.C." written beside it; the text of the Holy Scripltures' subsequent dramas, from Cain and Abel onward, had progressively lower and lower red-printed figures in the margin, until the events in the manger in Bethlehem, by which time the figure had been cycled down to a zero.
Wikipedia had this in its entry for Ussher:
Although Ussher produced a considerable number of religious works, his most famous was the Annales veteris testamenti, a prima mundi origine deducti ("Annals of the Old Testament, deduced from the first origins of the world"), published in 1650. In this work, he claimed, infamously, that the earth was created on the evening preceding October 23, 4004 BC. This work established what has become known as the Ussher-Lightfoot Calendar. It is a work that is still referenced by Young Earth Creationists (who believe that the Earth is approximately 6,000 years old) and has been much ridiculed as a symbol of religious obscurantism. The time is frequently misquoted as being 9 a.m., noon or 9 p.m. on October 23. See the related article on the Calendar for a discussion of its claims and methodology.
The Calender reference above is to:
The Ussher-Lightfoot Calendar is a 17th century chronology of the history of the world formulated from an interpretative reading of the Bible by James Ussher, the Anglican Archbishop of Armagh (in what is now Northern Ireland). The chronology, first published in 1650, is famously the source of the citation by many modern Creationists that the universe was created by God in 4004 BC.
The chronology is named for Ussher, as well as John Lightfoot, who published a similar chronology in 1642–1644. The chronology is, however, arguably misnamed, as it based on Ussher's work, and not on that of Lightfoot, who was later the Vice-Chancellor of Cambridge University. Ussher's work, more properly known as the Annales veteris testamenti, a prima mundi origine deducti (Annals of the Old Testament, deduced from the first origins of the world), was his contribution to the long-running theological debate on the age of the Earth. This was a major concern of many Christian scholars over the centuries. Ussher deduced that the first day of Creation began at nightfall preceding Sunday October 23, 4004 BC in the proleptic Julian calendar, near the autumnal equinox, while Lightfoot similarly deduced that Creation began at nightfall near the autumnal equinox, but in the year 3929 BC.
Ussher's proposed date of 4004 BC was not greatly different from the estimates of the Venerable Bede (3952 BC) or Ussher's near-contemporary, Scaliger (3949 BC). It was widely believed that the Earth's potential duration was 6,000 years (4,000 before the birth of Christ and 2,000 after) corresponding to the six days of Creation, on the grounds that "one day is with the Lord as a thousand years, and a thousand years as one day" (2 Peter 3:8 ).