IPA: /ˌsʌbˈluːnəri/
KK: /sʌbˈluːnəri/
Relating to the earthly world or things that are not heavenly; situated beneath the moon.
The philosopher discussed the differences between sublunary and celestial matters.
Sublunary → It is formed from "sub-" (meaning under) and "lunaris" (from Latin "luna", meaning moon). The term refers to things that are under the moon, or earthly, as opposed to celestial or heavenly.
Think of things that are 'under' ('sub-') the 'moon' ('luna') — that's why sublunary refers to earthly matters.