Don't blame the dictionary too much!

Frequently a "translating" dictionary is also something of a thesaurus. Most languages have several words which cluster around a definition, with slightly differing meanings, and single words with serveral definitions. The dictionary maker either has to create something along the lines of the OED or hope that the person using the book is at least somewhat conversant with both languages.

Which is why you should always get a native speaker to check your work...