IPA: /sɜːrˈkʌm.lʊ.nər/
KK: /sɜrˈkʌmˌlunər/
Relating to something that revolves around or is situated around the moon.
The circumlunar mission aimed to study the moon's surface and its environment.
Circumlunar → It is formed from "circum-" (meaning around) and "lunar" (from Latin "lunaris", meaning of the moon). The word "circumlunar" refers to something that is situated or occurring around the moon.
Think of going 'around' ('circum-') the 'moon' ('lunar') — that's what circumlunar means.
No commonly confused words.