To grumble, fuss, or sulk; to be unsettled or irritable—often used about children or babies who whine or cry persistently.
赤ちゃんが夜中にぐずって眠れなかった。
The baby fussed all night and I couldn't sleep.
約束が破られて彼はぐずっていた。
He was grumbling because the promise was broken.
雨でピクニックが中止になり、子どもたちがぐずり始めた。
The picnic was canceled due to rain, and the children began to sulk.