Where does “mustahapero” come from?

mustahapero (Finnish) comes from Finnish hapero, from Finnish hapera, from Finnish haprea, from Finnish hauras, from Proto-Finnic hapras — brittle, fragile, weak.

mustahapero (Finnish): blackening russula, Russula nigricans

Definitions

blackening russula, Russula nigricans

Ancestry of “mustahapero”, step by step

mustahapero traces back through two separate lines of ancestry.

via Finnish hapero

Step	Language	Word	Meaning
1	Finnish	hapero	brittlegill, russula; brittle
2	Finnish	hapera	brittle
3	Finnish	haprea	—
4	Finnish	hauras	brittle, fragile, frail, friable, crumbly,...
5	Proto-Finnic	hapras	brittle, fragile, weak

via Finnish musta

Step	Language	Word	Meaning
1	Finnish	musta	black; black horse; Elative singular form of...
2	Finnish	-ntää	Front vowel variant of -ntaa

Every word from Proto-Finnic hapras →Every word from Finnish hauras →Every word from Finnish haprea →