A fellow member of the same club; someone who shares club membership with another person.
From 'club' plus 'mate' (meaning 'companion' or 'friend'). Modern term that emerged in the 19th-20th centuries to describe the bonds between club members.
The word 'clubmate' is interesting because it suggests friendship, but in actual club culture, you could be clubmates with someone you disliked—the club just threw you together with whoever else had the money and connections to join.
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