What is O' supposed to mean?

Oliveira   Friday, July 09, 2004, 17:37 GMT
Hello folks.
I've seen the term o' (o + apostrophe), but I can't figure out what it means.
I found it in the title of a song: Sweet Child O' Mine and in an ad which said: New Editions for the Good O' Fellows.
Could anybody help me with that? I guess it might be some abbreviation or short form for another word... Anyway I'm not aware of its real meaning and origin.

Thanks in advance.
Eastie   Friday, July 09, 2004, 18:03 GMT
O' = of (ex: lots o' luck; top o' the mornin')

"New Editions for the Good O' Fellows."

Are you sure the ad didn't say "good ol' fellows"? In this case, ol' means "old".
mjd   Friday, July 09, 2004, 18:06 GMT
"Sweet Child O' Mine" = sweet child OF mine. When this phrase is said very fast, it can sound like "sweet child o'mine"....same as "top o' the mornin'" etc.
Oliveira   Friday, July 09, 2004, 19:02 GMT
Thank you guys for your replies.
By the way, Eastie, the ad really says "New Editions for the Good O' Fellows."
I have it on a magazine advertising some English-learning material.
Now I just can't figure what they meant with that...
Jim   Sunday, July 11, 2004, 23:55 GMT
I think it would still mean "old".
Paul   Tuesday, July 13, 2004, 18:24 GMT
Auld is another form of Old.
CalifJim   Sunday, July 18, 2004, 04:57 GMT
And don't forget "o'clock", originally "OF the clock".