Parabolic; Parabolical

Part of speech: adjective (a.)

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

2. Having the form or nature of a parabola; pertaining to, or resembling, a parabola; as, a parabolic curve.

3. 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.