Where does “semenarche” come from?

semenarche (English) comes from English semen, from Middle English semen, from Old Norse sœma, from Proto-Germanic sōmijaną, from Proto-Indo-European sem- — together, one.

Ancestry of “semenarche”, step by step

Step	Language	Word	Meaning
1	English	semen	A sticky, milky fluid produced in male...
2	Middle English	semen	to seem
3	Old Norse	sœma	to honour, be content, beseem; to conform to,...
4	Proto-Germanic	sōmijaną	to fit, unite, make one
5	Proto-Indo-European	sem-	together, one

Every word from Proto-Indo-European sem- →