| parabolical | 1. Of the nature of a parable; expressed by a parable or figure; allegorical; as, parabolical instruction. 2. [From Parabola. <geometry> Having the form or nature of a parabola; pertaining to, or resembling, a parabola; as, a parabolic curve. 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. <optics> Parabolic mirror, 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. Origin: Gr. Figurative: cf. F. Parabolique. See Parable. Source: Websters Dictionary (01 Mar 1998) |
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