Here are a few possibilities:
* Root (noun): This is the most direct derivative, simply the noun form of the word.
* Rooted (adjective): Means "fixed or firmly established."
* Rootless (adjective): Means "lacking roots or a foundation."
* Rootstock (noun): The main root of a plant, from which other roots grow.
* Rootlet (noun): A small root.
* Radicle (noun): The first root to emerge from a seed.
* Radical (adjective): Means "relating to the root of something, fundamental or extreme."
Other possibilities:
* Root word: This is a term used in linguistics to describe a basic word from which other words are derived.
* Etymology: The study of the origin of words.
The specific meaning of the derivative will depend on the context in which it is used.