the.com/member

means A person or thing belonging to a group, or a distinct part belonging to a larger body or structure.

from From Latin 'membrum,' meaning a limb or body part — an arm, leg, or organ that belongs to the whole body. The word kept that logic as it moved into English: a 'member' of a club or organization is one part belonging to a larger whole, just as a limb belongs to a body. The anatomical sense never fully vanished either, which is why 'member' can still mean a bodily part, including as an old euphemism for genitals — a usage that's faded but explains some otherwise-puzzling old texts.