Definitions
1.nounA small, rounded, transparent, and domestic aquarium.
2.noun(by extension) Any place or event that lacks privacy or is intensely scrutinized.
3.nounA variety of discussions where participants are organized in concentric circles and take turns where they and others in the same group are allowed to speak according to a set of rules.
4.nounThe central and smallest circle where the speakers are located in some versions of such a discussion.