death-watch n.

Old English deaþ "total cessation of life, act or fact of dying, state of being dead; cause of death," in plural, "ghosts," from Proto-Germanic *dauthuz (source also of Old Saxon doth, Old Frisian dath, Dutch dood, Old High German tod, German Tod, Old Norse dauði, Danish død, Swedish död, Gothic dauus "death"), from verbal stem *dau-, which is perhaps from PIE root *dheu- (3) "to die" (see die (v.)). With Proto-Germanic *-thuz suffix indicating "act, process, condition."

I would not that death should take me asleep. I would not have him meerly seise me, and onely declare me to be dead, but win me, and overcome me. When I must shipwrack, I would do it in a sea, where mine impotencie might have some excuse; not in a sullen weedy lake, where I could not have so much as exercise for my swimming. [John Donne, letter to Sir Henry Goodere, Sept. 1608]

Of inanimate things, "cessation, end," late 14c. From late 12c. as "death personified, a skeleton as the figure of mortality." As "a plague, a great mortality," late 14c. (in reference to the first outbreak of bubonic plague; compare Black Death). Death's-head, a symbol of mortality, is from 1590s. Death's door "the near approach of death" is from 1540s.

As a verbal intensifier "to death, mortally" (as in hate (something) to death) 1610s; earlier to dead (early 14c.). Slang be death on "be very good at" is from 1839. To be the death of "be the cause or occasion of death" is in Shakespeare (1596). Expression a fate worse than death is from 1810 though the idea is ancient.

Death row "part of a prison exclusively for those condemned to capital execution" is by 1912. Death knell is attested from 1814; death penalty "capital punishment" is from 1844; death rate from 1859. Death-throes "struggle which in some cases accompanies death" is from c. 1300.

Old English wæcce "a watching, state of being or remaining awake, wakefulness;" also "act or practice of refraining from sleep for devotional or penitential purposes;" from wæccan "keep watch, be awake," from Proto-Germanic *wakjan, from PIE root *weg- "to be strong, be lively."

From c. 1200 as "one of the periods into which the night is divided," in reference to ancient times translating Latin vigilia, Greek phylake, Hebrew ashmoreth. From mid-13c. as "a shift of guard duty; an assignment as municipal watchman;" late 13c. as "person or group obligated to patrol a town (especially at night) to keep order, etc."

Also in Middle English, "the practice of remaining awake at night for purposes of debauchery and dissipation;" hence wacches of wodnesse "late-night revels and debauchery." The alliterative combination watch and ward preserves the old distinction of watch for night-time municipal patrols and ward for guarding by day; in combination, they meant "continuous vigilance."

Military sense of "military guard, sentinel" is from late 14c. General sense of "careful observation, watchfulness, vigilance" is from late 14c.; to keep watch is from late 14c. Meaning "period of time in which a division of a ship's crew remains on deck" is from 1580s. The meaning "small timepiece" is from 1580s, developing from that of "a clock to wake up sleepers" (mid-15c.).

The Hebrews divided the night into three watches, the Greeks usually into four (sometimes five), the Romans (followed by the Jews in New Testament times) into four. [OED]

On þis niht beð fowuer niht wecches: Biforen euen þe bilimpeð to children; Mid-niht ðe bilimpeð to frumberdlinges; hanecrau þe bilimpeð þowuene men; morgewile to alde men. [Trinity Homilies, c. 1200]