meal (n.1)

"by pieces, in pieces, piece by piece, bit by bit," c. 1300, pece-mele, from piece (n.1) + Middle English meal "fixed time, period of time, occasion," from Old English mælum "at a time," dative plural of mæl "appointed time, food served" (see meal (n.1)). The second element once was more common, as in Old English styccemælum "bit by bit." Compare gearmælum "year by year," and inchmeal.

"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]