什么是milling crowds?

问题描述:

什么是milling crowds?
milling在这里的意思不明白,请指教,

成群乱转的人
mill vi.
(人,家畜)成群地乱转[(+about/around)]
There's a huge crowd of people milling around in front of the theater.
一大群人在剧院门前转来转去.