Proper usage of the word "o'clock"

[cousette]

What is the proper way to use the word "o'clock"? I have always used this word with the hour, for example, one o'clock, two o'clock, three o'clock, etc. My son says it's OK to use the word "o'clock" with other times, for example, eight-thirty o'clock. Could you please explain the proper usage of the word? Thank you.

[engee30]

What is the proper way to use the word "o'clock"? I have always used this word with the hour, for example, one o'clock, two o'clock, three o'clock, etc. My son says it's OK to use the word "o'clock" with other times, for example, eight-thirty o'clock. Could you please explain the proper usage of the word? Thank you.

I'm afraid your son is wrong about it.

[Monticello]

I'm afraid your son is wrong about it.

"Right" or "wrong" may here depend on regional usages.

Though most often used and heard with "on the hour" times, o'clock, being simply a contraction for "of the clock," may be used with any other clock times.

For real-life examples of such usage, please see this Google search, 8:30 o'clock, which, as of today, May 2, 2009, returns about 28,700 entries.