Part 12

2. To enlighten; to illuminate; to shed light or brightness on; to irradiate. [R.]

Ra"di*ate (-t), a. [L. radiatus, p. p.] 1. Having rays or parts diverging from a center; radiated; as, a radiate crystal.

2. (Bot.) Having in a capitulum large ray florets which are unlike the disk florets, as in the aster, daisy, etc.

3. (Zoöl.) Belonging to the Radiata.

Ra"di*ate, n. (Zoöl.) One of the Radiata.

Ra"di*a`ted (-`td), a. 1. Emitted, or sent forth, in rays or direct lines; as, radiated heat.

2. Formed of, or arranged like, rays or radii; having parts or markings diverging, like radii, from a common center or axis; as, a radiated structure; a radiated group of crystals.

3. (Zoöl.) Belonging to the Radiata.

Ra"di*ate*ly (-t*l), adv. In a radiate manner; with radiation or divergence from a center.

Ra"di*ate-veined` (-vnd`), a. (Bot.) Having the principal veins radiating, or diverging, from the apex of the petiole; -- said of such leaves as those of the grapevine, most maples, and the castor-oil plant.

Ra`di*at"i*form (-t"*fôrm), a. (Bot.) Having the marginal florets enlarged and radiating but not ligulate, as in the capitula or heads of the cornflower. Gray.

Ra`di*a"tion (-"shn), n. [L. radiatio: cf. F. radiation.] 1. The act of radiating, or the state of being radiated; emission and diffusion of rays of light; beamy brightness.

2. The shooting forth of anything from a point or surface, like the diverging rays of light; as, the radiation of heat.

Ra"di*a*tive (r"d**tv), a. Capable of radiating; acting by radiation. Tyndall.

Ra"di*a`tor (-`tr), n. That which radiates or emits rays, whether of light or heat; especially, that part of a heating apparatus from which the heat is radiated or diffused; as, a steam radiator.

Rad"i*cal (rd"*kal), a. [F., fr. L. radicalis having roots, fr. radix, -icis, a root. See Radix.] 1. Of or pertaining to the root; proceeding directly from the root.

2. 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.

3. (Bot.) (a) Belonging to, or proceeding from, the root of a plant; as, radical tubers or hairs. (b) 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.

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

5. (Math.) 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 √ (originally the letter r, the initial of radix, root), placed before any quantity, denoting that its root is to be extracted; thus, √a, or √(a + b). To indicate any other than the square root, a corresponding figure is placed over the sign; thus, a, 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.

Syn. -- Primitive; original; natural; underived; fundamental; entire. -- Radical, Entire. These words are frequently employed as interchangeable in describing some marked alteration in the condition of things. There is, however, an obvious difference between them. A radical cure, reform, etc., is one which goes to the root of the thing in question; and it is entire, in the sense that, by affecting the root, it affects in an appropriate degree the entire body nourished by the root; but it may not be entire in the sense of making a change complete in its nature, as well as in its extent. Hence, we speak of a radical change; a radical improvement; radical differences of opinion; while an entire change, an entire improvement, an entire difference of opinion, might indicate more than was actually intended. A certain change may be both radical and entire, in every sense.

Rad"i*cal (rd"*kal), n. 1. (Philol.) (a) A primitive word; a radix, root, or simple, underived, uncompounded word; an etymon. (b) 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.

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