Loose, slack, or relaxed; also used to describe something happening slowly or leisurely (mimetic).
冬服でウエストがゆるゆるで楽だ。
The winter clothes are loose around the waist and comfortable.
週末はゆるゆる過ごしてリフレッシュした。
I spent the weekend leisurely and refreshed myself.
予定はゆるゆるだから、急がなくていいよ。
The schedule is relaxed, so there's no need to hurry.