phrasal verb bunch
If people or things bunch up
or bunch together
, or if you bunch
, they move close
to each other so that they form a small tight
They were bunching up, almost treading upon each other's heels.
People were bunched up at all the exits.
If they need to bunch aircraft more closely together to bring in one that is short
of fuel, they will do so.
COBUILD Advanced English Dictionary. Copyright © HarperCollins Publishers