retrograde

Retrograde, from Latin retrogradus, means moving backward. In common use it denotes a reversal of progress or a backward motion. In astronomy, retrograde motion describes an apparent reversal of a planet’s motion against the background stars. This occurs because Earth and the other planet orbit the sun at different speeds; when Earth overtakes an outer planet or lags behind an inner planet, the planet appears to move briefly in the reverse direction. The motion is optical, not a literal reversal of the planet’s orbit. The term is used to distinguish this apparent motion from the planet’s true orbital path, and it is often illustrated by apparent loops in the planet’s path across the sky.

In astrology, retrograde planets are said to influence personality and events differently, with retrograde periods seen as times for reflection, revision, or internal focus. Scientific support for astrological interpretations is not established.

In music, retrograde refers to a melodic or rhythmic figure presented backward. In tonal and serial composition, a phrase may be played in retrograde, i.e., in reverse order. In a fugue or canon, a retrograde subject can appear as a structural device.

The term can also appear in other domains to denote reversal or backward direction, such as retrograde motion in mechanical or time-related contexts. Overall, retrograde conveys the idea of reversal—whether as a perceptual phenomenon in the sky, a symbolic interpretation in astrology, or a compositional device in music.