1. Movement or change from one member of a continuous series to the next: progression of the disease in stages.
2. A continuous series; a sequence: a progression of limousines. See Synonyms at series.
3. Mathematics A series of numbers or quantities in which there is always the same relation between each quantity and the one succeeding it.
a. A succession of tones or chords.
b. A series of repetitions of a phrase, each in a new position on the scale.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.