Progression (?), n. [L. progressio: cf. F. progression.]
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1. The act of moving forward; a proceeding in a course; motion onward.
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2. Course; passage; lapse or process of time.
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I hope, in a short progression, you will be wholly immerged in the delices and joys of religion. Evelyn.
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3. (Math.) Regular or proportional advance in increase or decrease of numbers; continued proportion, arithmetical, geometrical, or harmonic.
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4. (Mus.) A regular succession of tones or chords; the movement of the parts in harmony; the order of the modulations in a piece from key to key.
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Arithmetical progression, a progression in which the terms increase or decrease by equal differences, as the numbers {2, 4, 6, 8, 1010, 8, 6, 4, 2} by the difference 2.
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-- Geometrical progression, a progression in which the terms increase or decrease by equal ratios, as the numbers {2, 4, 8, 16, 32, 6464, 32, 16, 8, 4, 2} by a continual multiplication or division by 2.
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-- Harmonic progression, a progression in which the terms are the reciprocals of quantities in arithmetical progression, as 1/2, 1/4, 1/6, 1/8, 1/10.
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