Progression

progression
1. The act of moving forward; a proceeding in a course; motion onward.
2. Course; passage; lapse or process of time. I hope, in a short progression, you will be wholly immerged in the delices and joys of religion. (Evelyn)
3. (Science: mathematics) regular or proportional advance in increase or decrease of numbers; continued proportion, arithmetical, geometrical, or harmonic.
4. 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. Arithmetical progression, a progression in which the terms increase or decrease by equal differences, as the numbers by the difference 2. Geometrical progression, a progression in which the terms increase or decrease by equal ratios, as the numbers by a continual multiplication or division by 2. 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.
Origin: L. Progressio: cf. F. Progression.