Invitation is a word that carries immense importance when it comes to formal or informal communication. It is the token that signals the engagement of individuals or groups to join an event or gathering. Some synonyms for this word include summons, request, call, notification, and solicitation.
Each term has its own nuances and connotations. For instance, summons can suggest a formal, legal obligation to appear before a court or authority, whereas request is a polite appeal that leaves room for rejection. Notification communicates information without necessarily implying an active invitation. These and the other synonyms for "invitation" all serve to communicate the act of calling or inviting others to join in an activity or event.