Quick Definition: A small group of people that has temporarily broken off from a larger group.
A subset (also written SubSet) is a portion of a group that belongs to a larger party. It is natural for large groups of people to break up into smaller groups, especially in loud environments such as night clubs and bars. Thus, the sets that a PUA encounters often belong to a larger group.
PUAs can use this to their advantage, by referring to the people he encountered in earlier subsets to build rapport with the rest of their friends. This can also backfire, as a bad set earlier in the evening can come back to haunt you if it doesn’t go well, as the subset will go back and tell all their friends.
The term subset was developed by members of the NYC Lair (playing off the term “set” originally coined by Mystery). It is used as a way of conveying the group dynamics and relationships present in any given venue.
“This 2 subset is really part of a 5 set, the other 3 are on the other side of us.”
Source: Nathan PUA (NYC Lair Chief)