A non-meeting (n.) is a so-called meeting that lacks or does not possess the criteria in order to be a true meeting.
A: "That was a waste of an hour! We all sat in the room and shouted at each other, then we left. It was a non-meeting."
A: Meetings are permitted on Mondays, Wednesdays and Fridays - You cannot meet on a Tuesday; it is a non-meeting day. (It is not a day upon which meetings take place. - Tuesday does not meet the criteria for a meeting.)
No-meeting is the gerundive equivalent (n./adj.) of the imperative "Do not meet."
No-meeting day - a day upon which it is forbidden to meet/have a meeting
"Non-X" indicates a lack of "X"
"No-X" prohibits X
OED Non (prefix)
- Prefixed to nouns of action, condition, or quality with the sense ‘absence or lack of’, often corresponding semantically to ‘not doing,
failure to do’ (where a verb is implied by the noun, as in
non-accomplishment, lack of accomplishment, failure to accomplish) or
to ‘not being, failure to be’ (where an adjective is implied by the
noun, as in non-activity, lack of activity, failure to be active).
2.a. Prefixed to agent nouns and designations of persons and things, indicating that the person or thing is not that, or not of the sort,
specified.
2.b. spec. Prefixed to a noun, denoting a person or thing that is not really or adequately what is designated by the noun.