Someone who is not a member (of a club, institution, etc.)(noun)
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Use "non-member" in a sentence
"Hound Dog's castigation may be based on his generally poor opinion of the Lakeside population in general since he has no personal stake, as a non-member, in the Lake Chapala Society's existence or demise."
"The GA cannot admit a new state to the UN, but can elevate the Palestinians' current status to non-member observer state."
"However, when a newly elected member wishes a sword, a committee chaired by a non-member—usually a close friend—raises funds and oversees its design."