Definition of "gaggles"

There were no signs and no one quite knew how to navigate the museum, including, as it was Fleet Week, gaggles of boyish sailors all in their summer whites. It looked like a Frank Sinatra movie.

2014 June 7, Vicki Woods, “Sadness, and a surprise, at the 9/11 Museum: The memorial at Ground Zero is filled with objects that shock the tears out of you”, in The Daily Telegraph‎, page 24