What is the meaning of session?

noun

• A meeting for execution of a group's functions.
  • usage: "it was the opening session of the legislature"
• The time during which a school holds classes.
  • usage: "they had to shorten the school term"
  • synonyms: school term, academic term, academic session
• A meeting devoted to a particular activity.
  • usage: "a filming session"; "a gossip session"
• A meeting of spiritualists.
  • usage: "the seance was held in the medium's parlor"
  • synonyms: seance, sitting