Meanings of baggy knickers in English

He was wearing short socks and his legs were bare, sticking out of the baggy knickers.

A flurry of boots and baggy knickers mingle with pointing fingers and high-pitched chattering; soon 19 fully dressed Japanese are hopping about their tent city.

I suppose they'll resolve into baggy knickers and the sort of long shirt with a belt to it the youngsters of your age all wear.