Supposedly it was bad luck to use the real word for "bear"--a bear might suddenly appear, so "honey-eater" was used instead. English actually did something similar--our word for bear originally meant "the brown one."
It did? "Bear" in English sounds the same as and means the same things as "Bär" in German. A lot of the words for animals in English come from Anglo-Saxon which means they're the same or nearly the same in German. For example when it was in the field it was Swine ("Schwein"). When it was served on your dinner plate it was Pork ("porc" in French).