retrogradation

ret·ro·grade

 (rĕt′rə-grād′)

adj.

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.

4. Astronomy

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.

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[Middle English, from Latin retrōgradus, from retrōgradī, to go back : retrō-, retro- + -gradus, walking (from gradī, to go; see ghredh- in Indo-European roots).]

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ret′ro·gra·da′tion (-rō-grā-dā′shən) n.

ret′ro·grade′ly adv.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Thesaurus

retrogradation

noun

A return to a former, usually worse condition:

regression, retrogression, reversion.

The American Heritage® Roget's Thesaurus. Copyright © 2013, 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.