a small, thin rubber bag that you blow air into or fill with a light gas until it is round in shape, used for decoration, as a children's toy, or for other purposes such as medical treatment or scientific research :
We tied balloons and streamers to the ceiling ready for the party.
Angioplasty is a medical procedure in which a balloon is used to stretch open a narrow or blocked artery.
a very large balloon that is filled with hot air or gas and can carry people in a basket (= open container ) hanging under it:
People first flew in a balloon in 1783.
a round shape drawn next to the head of a character in a cartoon (= a story or joke told using drawings), in which the character's words or thoughts are written :
The words appear inside a cartoon-style balloon hovering above the figures.
He produced many of the best-known images of American Pop Art, especially frames from comic books complete with speech balloons.
You can edit the photos, for example by adding thought balloons.