I like your explanation using rings, and I'd say there is a ring 3 which is new acquaintances. For instance, someone who you're introduced to by a ring 1 or 2,

I like your explanation using rings, and I'd say there is a ring 3 which is new acquaintances. For instance, someone who you're introduced to by a ring 1 or 2, and end up hanging out with for the remainder of a night out. They're not as much a stranger as someone you pass on the sidewalk, but you only know about them based on what they've told you during this first extended encounter.