stump; rootstock
Refers to the base of a tree or plant left after cutting, including the roots. Used in gardening, forestry, and metaphorically for the root of a problem.
I struggled to dig up the old stump in the garden.
問題の根株を絶たなければ、同じことが繰り返されるだろう。
Unless we eliminate the root of the problem, the same thing will happen again.
Compound of 根 (ne, 'root') and 株 (kabu, 'stump, stock'). The reading ねかぶ is a straightforward combination.