When English is Not a DUer's First Language,

[Ednahilda]

8. Each and every person who has studied a foreign language has made a similar mistake.

I studied six languages at college as a f.l. major and I ALWAYS reverse-checked unfamiliar words to reduce the chances of doing just this! In your example, it would mean looking up 'bum' in the English to Russian dictionary, finding 'zadnitsa' as a possible translation, then looking up 'zadnitsa' in the Russian to English volume to make sure it's the meaning/shade of meaning you want. It isn't fool-proof, but it does eliminate some of the most embarrassing mistakes. This, of course, does not help when there isn't a corresponding word in the other language, which happens more often than one might imagine.

It is true that many (not all) English-to-Whatever dictionaries do use British English rather than American English, so if you've got one of those, be especially careful - there are two layers of potential mistakes built into that.