Root, Source, Origin, Foundation
noun, の adjective
The root origin is the root of something. Possibly even more root than root, but we'll stick with root.
こんぽん, ねもと
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Careful, 本 is ぽん, which is a weird rendaku.
私も父も根本の考え方は同じです。
My father and I have fundamentally the same way of thinking.
英語を根本から学び直したいです。
I want to re-learn English from the ground up.
この問題の根本の原因はどこにあると思いますか?
What do you think the fundamental cause of this problem is?