root
Definitions
The part of a plant that attaches it to the ground or to a support, typically underground, conveying water and nourishment to the rest of the plant.
The basic cause, source, or origin of something.
A number or quantity that, when multiplied by itself a specified number of times, produces a given number.
Examples
The tree's deep root system helps it survive during long periods of drought.
We need to get to the root of the problem before we can find a permanent solution.
The square root of sixty-four is eight.