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.

In politics they [the Independents] were, to use the phrase of their own time, "Root-and-Branch men," or, to use the kindred phrase of our own, Radicals.

Macaulay.

3. (Chem.) (a) 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.

(b) 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.

4. (Alg.) 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.)

5. (Anat.) A radical vessel. See under Radical, a.

Rad"i*cal*ism (-z'm), n. [Cf. F. radicalisme.] The quality or state of being radical; specifically, the doctrines or principles of radicals in politics or social reform.

Radicalism means root work; the uprooting of all falsehoods and abuses.

F. W. Robertson.

Rad`i*cal"i*ty (-kl"*t), n. 1. Germinal principle; source; origination. [Obs.] Sir T. Browne.

2. Radicalness; relation to a root in essential nature or principle.

Rad"i*cal*ly (rd"*kal*l), adv. 1. In a radical manner; at, or from, the origin or root; fundamentally; as, a scheme or system radically wrong or defective.

2. Without derivation; primitively; essentially. [R.]

These great orbs thus radically bright.

Prior.

Rad"i*cal*ness, n. Quality or state of being radical.

Rad"i*cant (-kant), a. [L. radicans, p. pr.: cf. F. radicant. See Radicate, a.] (Bot.) Taking root on, or above, the ground; rooting from the stem, as the trumpet creeper and the ivy.

Rad"i*cate (-kt), a. [L. radicatus, p. p. of radicari to take root, fr. radix. See Radix.] Radicated.

Rad"i*cate (-kt), v. i. To take root; to become rooted. Evelyn.

Rad"i*cate, v. t. [imp. & p. p. Radicated (-k`td); p. pr. & vb. n. Radicating.] To cause to take root; to plant deeply and firmly; to root.

Time should . . . rather confirm and radicate in us the remembrance of God's goodness.

Barrow.

Rad"i*ca`ted (-k`td), a. Rooted; specifically: (a) (Bot.) Having roots, or possessing a well-developed root. (b) (Zoöl.) Having rootlike organs for attachment.

Rad`i*ca"tion (-k"shn), n. [Cf. F. radication.] 1. The process of taking root, or state of being rooted; as, the radication of habits.

2. (Bot.) The disposition of the roots of a plant.

Rad"i*cel (rd"*sl), n. [Dim. of radix.] (Bot.) A small branch of a root; a rootlet.

Ra*dic`i*flo"rous (r*ds`*fl"rs), a. [L. radix, -icis, root + flos, floris, a flower.] (Bot.) Rhizanthous.

Ra*dic"i*form (r*ds"*fôm), a. (Bot.) Having the nature or appearance of a radix or root.

Rad"i*cle (rd"*k'l), n. [L. radicula, dim. of radix, -icis, root: cf. F. radicule. See Radix.] (Bot.) (a) The rudimentary stem of a plant which supports the cotyledons in the seed, and from which the root is developed downward; the stem of the embryo; the caulicle. (b) A rootlet; a radicel.

Ra*dic"u*lar (r*dk"*lr), a. Of or pertaining to roots, or the root of a plant.

Rad"i*cule (rd"*kl), n. (Bot.) A radicle.

Ra*dic"u*lose` (r*dk"*ls`), a. (Bot.) Producing numerous radicles, or rootlets.

Ra"di*i (r"d*), n., pl. of Radius.

Ra"di*o- (r"d*-). A combining form indicating connection with, or relation to, a radius or ray; specifically (Anat.), with the radius of the forearm; as, radio-ulnar, radio- muscular, radio-carpal.

||Ra`di*o-flag`el*la"ta (- flj`l*l"t), n. pl. [NL. See Radiate, and ||Flagellata.] (Zoöl.) A group of Protozoa having both flagella and ||pseudopodia.

Ra"di*o*graph (r"d**grf), n. [Radio- + -graph.] (Phys.) A picture produced by the Röntgen rays upon a sensitive surface, photographic or fluorescent, especially a picture of opaque objects traversed by the rays.

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||Ra`di*o*la"ri*a (r`d**l"r*), n. pl. [NL. See Radioli.] (Zoöl.) Order ||of rhizopods, usually having a siliceous skeleton, or shell, and ||sometimes radiating spicules. The pseudopodia project from the body ||like rays. It includes the polycystines. See Polycystina.

Ra`di*o*la"ri*an (r`d**l"r*an), a. (Zoöl.) Of or pertaining to the Radiolaria. -- n. One of the Radiolaria.

||Ra*di"o*li (r*d"*l), n. pl.; sing. Radiolus (-ls). [NL., dim. of L. ||radius radius: cf. L. radiolus a feeble sunbeam.] (Zoöl.) The barbs ||of the radii of a feather; barbules.

Ra"di*o*lite (r"d**lt), n. [L. radius ray + -lite: cf. F. radiolithe.] (Paleon.) A hippurite.

Ra`di*om"e*ter (-m"*tr), n. [L. radius radius + -meter: cf. F. radiomètre.] 1. (Naut.) A forestaff.

2. (Physics) An instrument designed for measuring the mechanical effect of radiant energy.

It consists of a number of light disks, blackened on one side, placed at the ends of extended arms, supported on a pivot in an exhausted glass vessel. When exposed to rays of light or heat, the arms rotate.

Ra`di*o*mi*crom"e*ter (- *m*krm"*tr), n. [Radio- + micrometer.] (Physics) A very sensitive modification or application of the thermopile, used for indicating minute changes of radiant heat, or temperature.

Ra"di*o*phone (r"d**fn), n. [Radio- + Gr. fwnh` sound.] (Physics) An apparatus for the production of sound by the action of luminous or thermal rays. It is essentially the same as the photophone.

Ra`di*oph"o*ny (-f"*n), n. (Physics) The art or practice of using the radiophone.

Ra"di*ous (r"d*s), a. [L. radiosus.] 1. Consisting of rays, as light. [R.] Berkeley.

2. Radiating; radiant. [Obs.] G. Fletcher.

Rad"ish (rd"sh), n. [F. radis; cf. It. radice, Pr. raditz; all fr. L. radix, -icis, a root, an edible root, especially a radish, akin to E. wort. See Wort, and cf. Eradicate, Race a root, Radix.] (Bot.) The pungent fleshy root of a well-known cruciferous plant (Raphanus sativus); also, the whole plant.

Radish fly (Zoöl.), a small two- winged fly (Anthomyia raphani) whose larvæ burrow in radishes. It resembles the onion fly. -- Rat-tailed radish (Bot.), an herb (Raphanus caudatus) having a long, slender pod, which is sometimes eaten. -- Wild radish (Bot.), the jointed charlock.

Ra"di*us (r"d*s), n.; pl. L. Radii (- ); E. Radiuses (-s*z). [L., a staff, rod, spoke of a wheel, radius, ray. See Ray a divergent line.] 1. (Geom.) A right line drawn or extending from the center of a circle to the periphery; the semidiameter of a circle or sphere.

2. (Anat.) The preaxial bone of the forearm, or brachium, corresponding to the tibia of the hind limb. See Illust. of Artiodactyla.

The radius is on the same side of the limb as the thumb, or pollex, and in man it is so articulated that its lower end is capable of partial rotation about the ulna.

3. (Bot.) A ray, or outer floret, of the capitulum of such plants as the sunflower and the daisy. See Ray, 2.

4. pl. (Zoöl.) (a) The barbs of a perfect feather. (b) Radiating organs, or color-markings, of the radiates.

5. The movable limb of a sextant or other angular instrument. Knight.

Radius bar (Mach.), a bar pivoted at one end, about which it swings, and having its other end attached to a piece which it causes to move in a circular arc. -- Radius of curvature. See under Curvature.

||Ra"di*us vec"tor (vk"tr). 1. (Math.) A straight line (or the length ||of such line) connecting any point, as of a curve, with a fixed ||point, or pole, round which the straight line turns, and to which it ||serves to refer the successive points of a curve, in a system of ||polar coördinates. See Coördinate, n.

2. (Astron.) An ideal straight line joining the center of an attracting body with that of a body describing an orbit around it, as a line joining the sun and a planet or comet, or a planet and its satellite.

Ra"dix (r"dks), n.; pl. L. Radices (rd"*sz), E. Radixes (r"dks*z). [L. radix, -icis, root. See Radish.] 1. (Philol.) A primitive word, from which spring other words; a radical; a root; an etymon.

2. (Math.) (a) A number or quantity which is arbitrarily made the fundamental number of any system; a base. Thus, 10 is the radix, or base, of the common system of logarithms, and also of the decimal system of numeration. (b) (Alg.) A finite expression, from which a series is derived. [R.] Hutton.

3. (Bot.) The root of a plant.

||Rad"u*la (rd"*l), n.; pl. Radulæ (- l). [L., a scraper, fr. radere to ||scrape.] (Zoöl.) The chitinous ribbon bearing the teeth of mollusks; ||-- called also lingual ribbon, and tongue. See Odontophore.