I asked the bear what the apple was like. He said 'underb(e)ar'. I asked him why he wasn't eating it. He said it was beneath him.
I'll get my coat.
I'm sure it's just one more synonym they didn't manually include yet. It probably seemed reasonable to think people would be content translating under into under ;).
You use spatial location verbs - mostly sitter, ligger, and står - for things that are situated in such positions. But apples don't really tend to sit, nor stand, so it doesn't make much sense to use either - at least not when they're under a bear! :) However, ligger is accepted.