Charter member and Fellow member

Charter member noun - One of the original members when an organization was founded.

Fellow member and charter member are semantically related. In some cases you can use "Fellow member" instead a noun phrase "Charter member".

Fellow member noun - One of the persons who compose a social group (especially individuals who have joined and participate in a group organization).

Charter member and fellow member are semantically related. Sometimes you can replace phrase "Charter member" with "Fellow member", this phrases are similar.