IPA: /ˌrɛtrəˈɡreɪdli/
KK: /rɛtrəˈɡreɪdli/
In a way that moves backward or in reverse.
The spacecraft moved retrogradely to avoid obstacles in its path.
Retrogradely → It is formed from "retro-" (meaning backward) and "gradus" (meaning step or degree) and the suffix "-ly" (meaning in a manner). The word "retrogradely" means in a manner that moves backward or in reverse steps.
Think of moving 'backward' ('retro-') in 'steps' ('gradus') — that's why retrogradely means to do something in a backward manner.
No commonly confused words.