Where does “Mesoarchaikum” come from?

Mesoarchaikum (German) comes from German Archaikum, from New Latin Archaicum.

Ancestry of “Mesoarchaikum”, step by step

Step	Language	Word	Meaning
1	German	Archaikum	Archaean
2	New Latin	Archaicum	—

Mesoarchaikum — Etymology, Origin & Word History | Etymology Explorer