Definitions for radicals
The Nuttall Encyclopedia
a class of English politicians who, at the end of the 18th century and the beginning of the 19th, aimed at the political emancipation of the mass of the people by giving them a share in the election of parliamentary representatives. Their Radicalism went no farther than that, and on principle could not go farther.
The Standard Electrical Dictionary
A portion of a molecule, possessing a free bond and hence free to combine directly. A radical never can exist alone, but is only hypothetical. An atom is a simple radical, an unsaturated group of atoms is a compound radical.