"Radical" is a word in ENGLISH

A radical quantity. See under Radical, a.

A characteristic, essential, and fundamental constituent
of any compound; hence, sometimes, an atom.

Of or pertaining to the root; proceeding directly from the
root.

A primitive letter; a letter that belongs to the radix.

Specifically, a group of two or more atoms, not completely
saturated, which are so linked that their union implies certain
properties, and are conveniently regarded as playing the part of a
single atom; a residue; -- called also a compound radical. Cf. Residue.

Of or pertaining to a radix or root; as, a radical
quantity; a radical sign. See below.

One who advocates radical changes in government or social
institutions, especially such changes as are intended to level class
inequalities; -- opposed to conservative.

Hence: Of or pertaining to the root or origin; reaching to
the center, to the foundation, to the ultimate sources, to the
principles, or the like; original; fundamental; thorough-going;
unsparing; extreme; as, radical evils; radical reform; a radical party.

A radical vessel. See under Radical, a.

Relating, or belonging, to the root, or ultimate source of
derivation; as, a radical verbal form.

Proceeding from a rootlike stem, or one which does not
rise above the ground; as, the radical leaves of the dandelion and the
sidesaddle flower.

Belonging to, or proceeding from, the root of a plant; as,
radical tubers or hairs.

A primitive word; a radix, root, or simple, underived,
uncompounded word; an etymon.