**Par`a*bol"ic** (?), **Par`a*bol"ic*al** (?), a. [Gr. 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.

© Webster 1913.