noun course; passage; lapse or process of time.
2. progression ·noun the act of moving forward; a proceeding in a course; motion onward.
3. progression ·noun regular or proportional advance in increase or decrease of numbers; continued proportion, arithmetical, geometrical, or harmonic.
4. progression ·noun 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.