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unwillingly; reluctantly; grudgingly
shaking one's head in refusal (like a child)
いやいやながらも引き受けた仕事を最後までやった。
I reluctantly took on the work but saw it through to the end.
子供がいやいや野菜を食べている姿が微笑ましい。
It is charming to see a child eating vegetables reluctantly.
いやいや始めた趣味がいつの間にか本気になった。
A hobby I started reluctantly became serious before I knew it.