動詞 retrograde:

1. move backward in an orbit, of celestial bodies
2. move in a direction contrary to the usual one
3. move back
   同義詞：retreat
4. go back over
   同義詞：rehash, hash over
5. get worse or fall back to a previous condition
   同義詞：regress, retrogress

形容詞 retrograde:

1. moving from east to west on the celestial sphere; or--for planets--around the sun in a direction opposite to that of the Earth
2. of amnesia; affecting time immediately preceding trauma
3. going from better to worse
   同義詞：retrogressive
4. moving or directed or tending in a backward direction or contrary to a previous direction
   同義詞：retral

ret.ro.grade

adj.（形容詞）
Moving or tending backward.
后退的：向后移動的或向后傾的
Opposite to the usual order; inverted or reversed.
顛倒的：與通常順序相對的；倒轉的或顛倒的
Reverting to an earlier or inferior condition.
退化的：回到較早或較低級的狀態(tài)的
Astronomy
【天文學】
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.
逆行的：行星或其它天體沿軌道旋轉或繞軸旋轉的，該天體順著與大多數(shù)天體相反的方向由東向西順時針運動
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.
后退的：行星所做的短暫有規(guī)律的運動的，以靜止星體為參照物進行觀察時，這種運動顯然是后退的，這是由地球和所觀察天體具有不同的軌道速度引起的
Archaic Opposed; contrary.
【古語】 對立的：相對的；相反的
v.intr.（不及物動詞）
ret.ro.grad.ed,ret.ro.grad.ing,ret.ro.grades
To move or seem to move backward.See Synonyms at recede
后退，逆行：向后移動或似乎向后移動參見 recede
To decline to an inferior state; degenerate.
退步：降至較低級的狀態(tài)；退化

來源：
Middle English
中古英語
from Latin retrôgradus
源自 拉丁語 retrôgradus
from retrôgrado [to go back]
源自 retrôgrado [回去]
retrô- [retro-]
retrô- [表.后退的.]
-gradus [walking] from grado [to go] * see ghredh-
-gradus [步行] 源自 grado [去] *參見 ghredh-

【引伸】
ret.rograda.tion
ret.rograde.ly
adv.（副詞）