ORRERY n.
An apparatus which illustrates, by the revolution of balls moved by wheelwork, the relative size, periodic motions, positions, orbits, etc., of bodies in the solar system.
PALINGENESIS; PALINGENESY n.
That form of evolution in which the truly ancestral characters conserved by heredity are reproduced in development; original simple descent; -- distinguished from kenogenesis. Sometimes, in zoölogy, the abrupt metamorphosis of insects, crustaceans, etc.
PARABOLIC; PARABOLICAL a.
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 t…
PARADE n. 2 definitions
mbly and orderly arrangement or display of troops, in full equipments, for inspection or evolutions before some superior officer; a review of troops. Parades are general, regimental, or private (troop, battery, or company), according to the force assembled.
PERIOD n. 2 definitions
time as limited and determined by some recurring phenomenon, as by the completion of a revolution of one of the heavenly bodies; a division of time, as a series of years, months, or days, in which something is completed, and ready to recommence and go on in the same order; as, the period of the sun, or the earth, or a…