An original member or a founder of an organization.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "charter member" in a sentence
"The SETP would welcome Neil as a charter member and later elect him one of its distinguished Fellows."
"A charter member of Women In Film, she served as president and was honored in 2000 with its prestigious Crystal Award."
"And Donald G. Mitchell, to make an end of dull names, bulked so grandly in the academic eye that he was snatched from his tear-jugs and his tea-pots to become a charter member of the National Institute of Arts and Letters, and actually died a member of the American Academy!"