William the Conqueror invaded England and defeated King Harold at the Battle of Hastings in 1066.
In 1085, William decided to find out exactly how much his new kingdom was worth. According to an entry in the Anglo-Saxon Chronicle, the new king sent agents “all over England to each shire to find out what or how much each landholder had in land and livestock and what it was worth.”
William’s survey was completed in 1086. The results were recorded in a very large book. At the time, it was probably called something like “the survey book.”
Nearly 100 years later, this tax-assessment document had acquired the nickname “Domesday Book.”

Domesday is an older form of modern English Doomsday. The original meaning of doom as a noun is judgment.
Doom as a verb means, “to judge,” as in this quotation from Moby Dick:
Who’s to doom when the judge himself is dragged to the bar?
In religious belief, Doomsday is the end of the world. According to Christian belief, it is the time when individual souls will be judged according to the actions of their lives. Those judged worthy will go to a place of reward. Those who lived evil lives will go to a place of punishment. The chief characteristic of Doomsday is that the judgments made on that day are final. Negotiation is not an option.
William’s tax document acquired the name “Domesday Book” as a wry witticism. Writing in 1179, a financial officer named Richard FitzNeal explained the nickname:
for as the sentence of that strict and terrible last account [the Last Judgment] cannot be evaded by any skilful subterfuge, so when this book is appealed to … its sentence cannot be quashed or set aside with impunity. That is why we have called the book ‘the Book of Judgement’Â … because its decisions, like those of the Last Judgement, are unalterable.
“Death and taxes,” then as now.
You can find a more detailed account of the Domesday Book here: History Magazine.