One Merriam-Webster dictionary defines a meeting as "an act or process of coming together" - for example "as [...] an assembly for a common purpose [...]".
[1][3] Anthropologist Helen B. Schwartzman defines a meeting as "a communicative event involving three or more people who agree to assemble for a purpose ostensibly related to the functioning of an organization or group.
"[4] The term "meeting" may refer to a lecture (one presentation), seminar (typically several presentations, small audience, one day), conference (mid-size, one or more days), congress (large, several days), exhibition or trade show (with staffed stands being visited by passers-by), workshop (smaller, with active participants), training course, team-building session and kick-off event.
In informal meetings the participants often decide for themselves who turn taking functions with the chair occasionally intervening.
In these cases, the speaker may introduce the subject matter of the turn and related it to the agenda topic.