Crossword Dictionary

What's The Definition Of Parabolic?

\Par`a*bol"ic\, Parabolical \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.