Where does “среднемесячный” come from?
среднемесячный (Russian) comes from Russian ме́сячный, from Russian ме́сяц, from Old East Slavic мѣсѧць, from Proto-Slavic měsęcь, from Proto-Indo-European mḗh₁n̥s, from Proto-Indo-European meh₁- — to measure.
среднемесячный (Russian): average monthly
Ancestry of “среднемесячный”, step by step