dead [OE] Dead is related to Dutch dood and German Tod ‘death’, and to death [OE] itself. Their shared ancestor is the origin of *die. Often it is not enough to be dead: someone must be as dead as a doornail [LME] or as a *dodo [E20th]. The comparison with the extinct dodo is understandable enough, but it is not clear why doornails are particularly associated with death. A doornail was one of the large iron studs that were once used on doors to give additional strength or simply for decoration. It may also have been the large stud struck by the knocker, which, subject to constant pounding, could be considered well and truly dead. The phrase goes back to the Middle Ages and was used by Shakespeare, in whose time a person could also be as dead as a herring. That nothing is certain but death and taxes has been a view since the early 18th century. The original deadline [M19th] was a line drawn around a military prison, beyond which any prisoner was liable to be shot. It is first mentioned in a document of the 1860s.