text: what does " o' " mean? i've tried to google this but i can't find anything.   i know one of the most commonly thought of is the o' is o'clock which i've heard means "of the clock", but what about "o' wise one" (or is that actually ol' {old} wise one?) or "o' lord"?   are there any other words that start with o'? o is a word in english, used as an interjection to indicate the vocative case, as in "o ye of little faith!" so, when it's used like that...as in o lord or o wise one, it means you are calling out to someone.   o'clock is a different case. here, it means of (or according to) the clock. this is just a shortened form of the original phrasing...like it's 5 of the clock.