My Canadian Oxford Dictionary says that the word "bum" is used in only Canada and the UK (and I suppose other Commonwealth nations?) to mean buttocks/bottom/ass. It indicates that in the US, "bum" does not take on this meaning. Of course, as in the US, we also understand it to mean a lazy/homeless/poor/unemployed person, like "hobo" (but somewhat more derogatory). For us, this is only a secondary meaning.

I had always wondered why on earth Wal-Mart carries a line of clothing with initials B. U. M. on it, but when I read this I decided that maybe it's not offensive to US'ns, and it wouldn't be the first time that a company had no idea how to sell something to Canadians. I don't find it offensive, exactly, but I wouldn't write it on my clothes!

So, English speakers of the world, please let me know. When I first say the word "bum" to you, which meaning comes to your mind? Person or anatomy?