bubble

A spherically contained volume of air or other gas, especially one made from soapy liquid.

A small spherical cavity in a solid material.

(by extension) Anything resembling a hollow sphere.

(figuratively) Anything lacking firmness or solidity; a cheat or fraud; an empty project.

(economics) A period of intense speculation in a market, causing prices to rise quickly to irrational levels as the metaphorical bubble expands, and then fall even more quickly as the bubble bursts.

(figuratively) The emotional and/or physical atmosphere in which the subject is immersed.

An officer's station in a prison dormitory, affording views on all sides.

(obsolete) Someone who has been ‘bubbled’ or fooled; a dupe.

A small, hollow, floating bead or globe, formerly used for testing the strength of spirits.

The globule of air in the chamber of a spirit level.

(Cockney rhyming slang) A laugh.

(Cockney rhyming slang) A Greek.

(computing, historical) Any of the small magnetized areas that make up bubble memory.

(poker) The point in a poker tournament when the last player without a prize loses all their chips and leaves the game, leaving only players that are going to win prizes. (e.g., if the last remaining 9 players win prizes, then the point when the 10th player leaves the tournament)

A group of people who are in quarantine together.

Short for travel bubble.

(television, slang) A bulb or lamp; the part of a lighting assembly that actually produces the light.