look up any word, like fleek:
 
1.
When a person's rearend sticks out far enough for a small child to hide under in an immense rain storm.
Lisa: Wow it's raining outside!

Cora: Look, Connor is hiding under that woman's Bumbrella!
Lisa: By the looks of that thing, he's going to stay dry.
Connor: I hope she doesn't have the E.D.!
by Lisa Billygoat August 03, 2010
 
2.
A piece of cardboard that a bum uses as an umbrella.
Wow, that bum is smart, he is using a bumbrella.
by a74r1 February 27, 2007
 
3.
anything a bum or person in need uses for an umbrella
I didn't realize it was going to rain today so I used a newspaper as a bumbrella.
by Kaptain Kuhkneevul September 23, 2012
 
4.
(noun) A female posterior that has an exaggerated horizontal vector that defies physics. Very round, very fit. See also onion.
"Check out that bumbrella! If it were raining we'd both stay dry!"
by Osc@r February 12, 2007
 
5.
A fanciful umbrella, made from a pole, curved at one end, and a bum. The bum-on-a-pole is used mainly for keeping off unwanted rain, but also, less commonly, for poking at people who are causing the user irritation. Poking someone with your bumbrella causes the recipient of the poke discomfort, but immense satisfaction to the bumbrella-user who is doing the poking, and is thus highly amusing to watch.
Man: You're bothering me.

(uses bumbrella as poking device.)

Woman: oooph! Don't poke me with you're bumbrella. It's uncomfortable, and weird.

Onlooker: Hahahaha. Bumbrellas, eh? Always fun to watch.
by indie-hood September 25, 2008