A bump results when two things hit against each each other, or when there’s a small collision. Bumps also appear on the body when a person gets hit or as a reaction to an illness or some type of natural cause. The word "bump" can be used as a noun or as a verb:
George bumped his head.
Try not to bump into the other cars when you park along the curb.
When Zooey bumped into some glasses at the store, they fell off of the shelf and shattered.
The taxi bumped into the trash can.
He got a bump on his head and a few bruises after he fell off of his skateboard. (This sentence uses "bump" as a noun.)
This creature has bumps all over its body.
We also use the word "bump" when there’s an accidental meeting with another person, usually in a public place:
Denise bumped into an old friend at the store. She hadn’t seen him in over ten years.
I bumped into Jennifer Lopez in the elevator the other day. She smiled at me.
Abdi bumped into his neighbor at the laundromat while he was doing his laundry.
The adjective form of this word is "bumpy."
This is a really bumpy road. It’s causing the entire car to shake.
My arm is all red and bumpy. I think I’m having an allergic reaction to something.
The flight became a little bumpy when the airplane hit some turbulence.