The end part of a banana normally possessing a brown vein through the pulp of the fruit. The brown vein, (resembling poop), determines this is the export end of the banana, else known on other beings as being the anus. Hence, bananus.
the bottom end of the banana which everyone takes off and nobody enjoys to eat a.k.a the butt of the banana
Justin: dude this banana is so good
Mitchell: i agree but i don't likethe bottom of it
Justin: yeah we should call it something
Mitchell: but what should we call it
Justin: oh! I know lets call it the bananus!
narrator: and thus a word is born