The base or part near the root of something (e.g., the base of a plant, tree, pillar, or the roots of one's hair).
木の根元に小さな花が咲いている。
Small flowers are blooming at the base of the tree.
杭は根元から腐っていた。
The stake had rotted from the base.
染めた髪の根元が黒く伸びてきた。
The roots of my dyed hair have grown out dark.
The root or source of a problem; the fundamental cause or origin of something.
問題の根元を探さないと同じミスが繰り返される。
Unless we find the root of the problem, the same mistakes will be repeated.
その噂の根元は匿名の掲示板だったらしい。
Apparently the source of that rumor was an anonymous forum.
争いの根元は単なる誤解だった。
The root cause of the dispute was merely a misunderstanding.