What made you want to look up xenial? Please tell us where you read or heard it (including the quote, if possible).
Black dog is an oft-used phrase to mean depression. Here's a link that attributes the phrase to Winston Churchill, but I suspect he didn't invent it. I like the way they described it though: Black Dog was Churchill's name for his depression, and as is true with all metaphors, it speaks volumes.
(Redirected from Black Bear) Black bear may refer to: Animals. American black bear (Ursus americanus), a North American bear species. Asian black bear (Ursus thibetanus), an Asian bear species.