Listen up, people.
I keep reading bits of narrative lately where a character who’s walking around aimlessly or randomly is described as “milling about.”
Milling about is not something one person does, or even two people. Milling about requires at least a small crowd. The “mill” part of the verb comes from the idea that the random circular motion of such a crowd resembles the rotary action of a mill wheel.
One person alone pace, or might wander about, but they aren’t going to be milling, even if they’re doing it with a friend.