RADICAL

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

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. The most determined exertions of that authority, against them, only showed their radical independence. Burke.

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

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.

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

Of or pertaining to a radix or root; as, a radical quantity; a radical sign. See below. Radical axis of two circles. (Geom.) See under Axis. -- Radical pitch, the pitch or tone with which the utterance of a syllable begins. Rush. -- Radical quantity (Alg.), a quantity to which the radical sign is prefixed; specifically, a quantity which is not a perfect power of the degree indicated by the radical sign; a surd. -- Radical sign (Math.), the sign sq. root (originally the letter r, the initial of radix, root), placed before any quantity, denoting that its root is to be extracted; thus, sq. roota, or sq. root(a + b). To indicate any other than the square root, a corresponding figure is placed over the sign; thus cube roota, indicates the third or cube root of a. -- Radical stress (Elocution), force of utterance falling on the initial part of a syllable or sound. -- Radical vessels (Anat.), minute vessels which originate in the substance of the tissues.

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

A primitive letter; a letter that belongs to the radix. The words we at present make use of, and understand only by common agreement, assume a new air and life in the understanding, when you trace them to their radicals, where you find every word strongly stamped with nature; full of energy, meaning, character, painting, and poetry. Cleland.

One who advocates radical changes in government or social institutions, especially such changes as are intended to level class inequalities; -- opposed to conservative. In politics they [the Independents] were, to use phrase of their own time. "Root-and-Branch men," or, to use the kindred phrase of our own, Radicals. Macaulay.

A characteristic, essential, and fundamental constituent of any compound; hence, sometimes, an atom. As a general rule, the metallic atoms are basic radicals, while the nonmetallic atoms are acid radicals. J. P. Cooke.

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.

A radical quantity. See under Radical, a. An indicated root of a perfect power of the degree indicated is not a radical but a rational quantity under a radical form. Davies & Peck (Math. Dict. )

A radical vessel. See under Radical, a.