Definition of retrogration in US English:

retrogration

noun

  • Retrogradation.

Origin

Mid 16th century; earliest use found in William Bourne (c1535–1582), writer on mathematics. Shortened from retrogradation. Compare retrogation.

Pronunciation

retrogration

/ˌrɛtrə(ʊ)ˈɡreɪʃn/