What's the o' in o'clock stand for?

Question

Is it of the? (Like, Tony O'Leary, for example) or is it ON the? Something else entirely?

Just curious! :)

Or-- is it on the hour, even?

Thanks in advance!

Answer 1

As has been noted, "o'clock" is short for "of the clock". The sense of this "of" might better be expressed here with "according to the clock". The fuller form of the expression is found as early as the late 14th century (in Chaucer).
http://www.randomhouse.com/wotd/index.pperl?date=19970102

But WHY such an expression? And why do we normally NOT say things like "four ten o'clock"? Perhaps this will help.

It all goes back to the origins of the mechanical clock itself and the very word "clock". "Clock" comes from Latin 'cloca' meaning "BELL". It was the term applied to the newer devices in use for measuring time in the thirteenth century. As the word itself suggests, the key feature of these clocks is the bell that chimed the hours In fact, these clocks, often set out in public in a tower to make it possible to notify everyone, did not necessarily have hands. The key thing, then, was notifying people of the HOUR of the day (NOT the minute, and not, at least at first, the quarter or half hour either).

This practice of marking/announcing the hours --and just the hours-- is echoed by the watchman's call "nine o'clock and all is well." Thus it is scarcely surprising that this way of expressing the time did not (and still does not, except in certain highly formal uses) state anything BUT the HOUR.
http://en.wikipedia.org/wiki/Clock#A_new_mechanism

So you may picture the situation around 1300 -- the bell in the 'clock tower' strikes ONE time announcing that the hour is "one of ['according to'] the clock

Answer 2

O' is short for Of.
ten o'clock = ten of (or according to) the clock.

Answer 3

It is an contraction for: "of the clock."

Answer 4

of the clock

Answer 5

http://www.thefreedictionary.com/o'clock

.........of or according to the clock.

Answer 6

(of the) clock

Answer 7

"of the clock"

Answer 8

of the clock...weird, huh?

Answer 9

What will said.