n.
Function: noun
Date: 1641
1 a : a root part b : a basic principle : FOUNDATION
2 a : ROOT 6 b : a sound or letter belonging to a radical
3 : one who is radical
4 : FREE RADICAL also : a group of atoms bonded together that is considered an entity in various kinds of reactions or as a subunit of a larger molecule
5 a : a mathematical expression indicating a root by means of a radical sign b : RADICAL SIGN