Part 51

Par"a*ble, v. t. To represent by parable. [R.]

Which by the ancient sages was thus parabled.

Milton.

Pa*rab"o*la (?), n.; pl. Parabolas (#). [NL., fr. Gr. &?;; -- so called because its axis is parallel to the side of the cone. See Parable, and cf. Parabole.] (Geom.) (a) A kind of curve; one of the conic sections formed by the intersection of the surface of a cone with a plane parallel to one of its sides. It is a curve, any point of which is equally distant from a fixed point, called the focus, and a fixed straight line, called the directrix. See Focus. (b) One of a group of curves defined by the equation y = axn where n is a positive whole number or a positive fraction. For the cubical parabola n = 3; for the semicubical parabola n = . See under Cubical, and Semicubical. The parabolas have infinite branches, but no rectilineal asymptotes.

||Pa*rab"o*le (?), n. [L., fr. Gr. &?;. See Parable.] (Rhet.) ||Similitude; comparison.

{ Par`a*bol"ic (?), Par`a*bol"ic*al (?), } a. [Gr. paraboliko`s figurative: cf. F. parabolique. See Parable.]

1. Of the nature of a parable; expressed by a parable or figure; allegorical; as, parabolical instruction.

2. [From Parabola.] (Geom.) (a) Having the form or nature of a parabola; pertaining to, or resembling, a parabola; as, a parabolic curve. (b) Generated by the revolution of a parabola, or by a line that moves on a parabola as a directing curve; as, a parabolic conoid.

Parabolic conoid, a paraboloid; a conoid whose directing curve is a parabola. See Conoid. -- Parabolic mirror (Opt.), a mirror having a paraboloidal surface which gives for parallel rays (as those from very distant objects) images free from aberration. It is used in reflecting telescopes. -- Parabolic spindle, the solid generated by revolving the portion of a parabola cut off by a line drawn at right angles to the axis of the curve, about that line as an axis. -- Parabolic spiral, a spiral curve conceived to be formed by the periphery of a semiparabola when its axis is wrapped about a circle; also, any other spiral curve having an analogy to the parabola.

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Par`a*bol"ic*al*ly (pr`*bl"*kal*l), adv. 1. By way of parable; in a parabolic manner.

2. In the form of a parabola.

Par`a*bol"i*form (-*fÙrm), a. [Parabola + -form.] Resembling a parabola in form.

Pa*rab"o*lism (p*rb"*lz'm), n. [From Parabola.] (Alg.) The division of the terms of an equation by a known quantity that is involved in the first term. [Obs.]

Pa*rab"o*list (-lst), n. A narrator of parables.

Pa*rab"o*loid (-loid), n. [Parabola + -oid: cf. F. paraboloÔde.] (Geom.) The solid generated by the rotation of a parabola about its axis; any surface of the second order whose sections by planes parallel to a given line are parabolas.

The term paraboloid has sometimes been applied also to the parabolas of the higher orders. Hutton.

Par`a*bo*loid"al (?), a. Of, pertaining to, or resembling, a paraboloid.

||Par`a*bron"chi*um (?), n.; pl. Parabronchia (#). [NL. See Para-, ||Bronchia.] (Anat.) One of the branches of an ectobronchium or ||entobronchium.

Par`a*cel"si*an (?), a. Of, pertaining to, or in conformity with, the practice of Paracelsus, a Swiss physician of the 15th century. Ferrand.

Par`a*cel"si*an, n. A follower of Paracelsus or his practice or teachings. Hakewill.

Par`a*cel"sist (?), n. A Paracelsian.

||Par`a*cen*te"sis (?), n. [L., fr. Gr. &?;, fr. &?; to pierce at the ||side, to tap.] (Med.) The perforation of a cavity of the body with a ||trocar, aspirator, or other suitable instrument, for the evacuation ||of effused fluid, pus, or gas; tapping.

{ Par`a*cen"tric (?), Par`a*cen"tric*al (?), } a. [Pref. para- + centric, - ical: cf. F. paracentrique.] Deviating from circularity; changing the distance from a center.

Paracentric curve (Math.), a curve having the property that, when its plane is placed vertically, a body descending along it, by the force of gravity, will approach to, or recede from, a fixed point or center, by equal distances in equal times; -- called also a paracentric. -- Paracentric motton or velocity, the motion or velocity of a revolving body, as a planet, by which it approaches to, or recedes from, the center, without reference to its motion in space, or to its motion as reckoned in any other direction.

Par`a*chor"dal (?), a. [Pref. para- + chordal.] (Anat.) Situated on either side of the notochord; -- applied especially to the cartilaginous rudiments of the skull on each side of the anterior part of the notochord. -- n. A parachordal cartilage.

Pa*rach"ro*nism (?), n. [Pref. para- + Gr. &?; time: cf. F. parachronisme.] An error in chronology, by which the date of an event is set later than the time of its occurrence. [R.]

Par"a*chrose (?), a. [Gr. &?; false coloring; para` beside, beyond + &?; color.] (Min.) Changing color by exposure Mohs.