From Longman Dictionary of Contemporary Englishmill around/about (something) phrasal verb informalCROWDif a lot of people mill around, they move around a place in different directions without any particular purpose Crowds of students were milling around in the street. There were a lot of people milling around the entrance. → mill→ See Verb table
Examples from the Corpus
mill around/about • Chesarynth gripped it convulsively at the strange sight of people milling around.• It was a dark overcast day; the people milling around all looked grey.• Two days later mobs milled around as William Lloyd Garrison began to speak.• The entire Project Eden team - or what was left of it - was milling around: cowed, shocked and submissive.• There were people milling around on the streets.• Previously, most local grain was ground in the many small mills around the city and outlying areas.• Shaken survivors milled about the lobby awaiting word on when they could leave Cairo.• People have been coming in and milling around to see if we actually have it. 