clepsydra n.

also cleptomania, 1830, formed from mania + Greek kleptes "thief, a cheater," from kleptein "to steal, act secretly," from PIE *klep- "to steal" (an extension of root *kel- (1) "to cover, conceal, save"); cognate with Latin clepere "to steal, listen secretly to," Old Prussian au-klipts "hidden," Old Church Slavonic poklopu "cover, wrapping," Gothic hlifan "to steal," hliftus "thief."

The word was much-derided in 19c. as a fancy term for old-fashioned thievery and an opportunity for the privileged to claim a psychological motive for criminal misbehavior.

There is a popular belief that some of the criminal laws under which the poor are rigorously punished are susceptible of remarkable elasticity when the peccadilloes of the rich are brought under judgment, and that there is some truth in the old adage which declares that "one man may steal a horse where another dare not look over the hedge." This unwholesome distrust is not likely to diminish if, in cases of criminal prosecutions where so-called respectable persons commit theft without sufficiently obvious motive for the act, they have their crime extenuated on the plea of kleptomania, as has recently occurred in several notable instances. ["Kleptomania," The Lancet, Nov. 16, 1861]

Proto-Indo-European root meaning "water; wet."

It forms all or part of: abound; anhydrous; carbohydrate; clepsydra; dropsy; hydra; hydrangea; hydrant; hydrargyrum; hydrate; hydraulic; hydro-; hydrogen; hydrophobia; hydrous; Hydrus; inundate; inundation; kirsch-wasser; nutria; otter; redound; redundant; surround; undine; undulant; undulate; undulation; vodka; wash; water (n.1); wet; whiskey; winter.

It is the hypothetical source of/evidence for its existence is provided by: Hittite watar, Sanskrit udrah, Greek hydor, Old Church Slavonic and Russian voda, Lithuanian vanduo, Old Prussian wundan, Gaelic uisge "water;" Latin unda "wave;" Old English wæter, Old High German wazzar, Gothic wato "water."

"machine to measure and indicate time mechanically" (since late 1940s also electronically), late 14c., clokke, originally "clock with bells," probably from Middle Dutch clocke (Dutch klok) "a clock," from Old North French cloque (Old French cloke, Modern French cloche "a bell"), from Medieval Latin clocca "bell," which probably is from Celtic (compare Old Irish clocc, Welsh cloch, Manx clagg "a bell") and spread by Irish missionaries (unless the Celtic words are from Latin). Ultimately of imitative origin.

Wherever it actually arose, it was prob. echoic, imitating the rattling made by the early handbells of sheet-iron and quadrilateral shape, rather than the ringing of the cast circular bells of later date. [OED]

Replaced Old English dægmæl, from dæg "day" + mæl "measure, mark" (see meal (n.1)). The Latin word was horologium (source of French horologe, Spanish reloj, Italian oriolo, orologio); the Greeks used a water-clock (klepsydra, literally "water thief;" see clepsydra).

The image of put (or set) the clock back "return to an earlier state or system" is from 1862. Round-the-clock (adj.) is from 1943, originally in reference to air raids. To have a face that would stop a clock "be very ugly" is from 1886. (Variations from c. 1890 include break a mirror, kill chickens.)

I remember I remember

That boarding house forlorn,

The little window where the smell

Of hash came in the morn.

I mind the broken looking-glass,

The mattress like a rock,

The servant-girl from County Clare,

Whose face would stop a clock.

[... etc.; The Insurance Journal, January 1886]