1. Moving or tending backward: a retrograde flow.
2. Opposite to the usual order; inverted or reversed: the retrograde form of the melody.
3. Reverting to an earlier or inferior condition: a retrograde way of thinking.
a. Of or relating to the orbital revolution or axial rotation of a planetary or other celestial body that moves clockwise from east to west, in the direction opposite to most celestial bodies.
b. Of or relating to the brief, regularly occurring, apparently backward movement of a planetary body in its orbit as viewed against the fixed stars, caused by the differing orbital velocities of Earth and the body observed.
c. Of or relating to orbital motion in the direction opposite that of the predominant motion in an orbital system.
intr.v. ret·ro·grad·ed, ret·ro·grad·ing, ret·ro·grades
1. Astronomy To have retrograde motion.
2. To decline to an inferior state; degenerate.
3. Archaic To move or seem to move backward.
[Middle English, from Latin retrōgradus, from retrōgradī, to go back : retrō-, retro- + -gradus, walking (from gradī, to go; see ghredh- in the Appendix of Indo-European roots).]
ret′ro·gra·dation (-rō-grā-dāshən) n.
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.