1. Taru adjective, Adverb taking the 'to' particle

   quiet; calm; leisurely; composed

   飛行機は頭上をゆうゆうと飛んで行った。

2. Adverb taking the 'to' particle, Adverb (fukushi)

   easily; comfortably; without difficulty

3. Taru adjective, Adverb taking the 'to' particle

   distant; far-off; boundless; endless; eternal

Also written 悠悠【ゆうゆう】yuuyuu