expression, godan verb (-ru)
become obstinate; get stubborn
Often used adverbially as 意地になって to describe doing something out of stubbornness or pride, refusing to back down.
See also: 意地になって
彼は意地になって、自分の間違いを認めようとしなかった。
He became obstinate and wouldn't admit his mistake.
意地になって最後までやり遂げた。
I stubbornly saw it through to the end.