Often abbrivated "BO", body odour (or body odor) refers to a usually unpleasant smell eminating from a person. This smell could be bad breath, stinky armpits, or even someone who hasn't washed themselves in quite a long time.
Body odour is one of those things people don't like to talk about. If the person next to you stinks, you don't tell them, it's just not polite to point things like that out. Unfortunatly, a lot of people go through life not knowing proper hygiene. I'm always amazed at how many people manage to bathe, brush their teeth, wash their hair, comb their hair, cut their nails, and yet not use deodorant. I've met corporate executives that smell like mountain men (and no, that's not a good thing.) One would think that if someone makes over one hundred thousand dollars a year, they could afford a stick of deodorant.