bubble
noun
a hollow globule of gas (e.g., air or carbon dioxide)
a speculative scheme that depends on unstable factors that the planner cannot control
“his proposal was nothing but a house of cards”
“a real estate bubble”
Synonymshouse of cardsan impracticable and illusory idea
“he didn't want to burst the newcomer's bubble”
a dome-shaped covering made of transparent glass or plastic
verb
form, produce, or emit bubbles
“The soup was bubbling”
flow in an irregular current with a bubbling noise
“babbling brooks”
rise in bubbles or as if in bubbles
“bubble to the surface”
cause to form bubbles
“bubble gas through a liquid”
expel gas from the stomach
“Please don't burp at the table”
Source: WordNet 3.1, Princeton University