Where does “svärmorbror” come from?

svärmorbror (Swedish) comes from Swedish svår, from Old Swedish svar, from Old Norse svárr, from Proto-Germanic swēraz, from Proto-Indo-European swēr- — heavy.

svärmorbror (Swedish): uncle-in-law; the maternal uncle of someone's spouse or the husband of someone's maternal aunt or uncle

Definitions

uncle-in-law; the maternal uncle of someone's spouse or the husband of someone's maternal aunt or uncle

Ancestry of “svärmorbror”, step by step

svärmorbror traces back through two separate lines of ancestry.

via Swedish svår

Step	Language	Word	Meaning
1	Swedish	svår	hard; difficult; troublesome and of bad temper;...
2	Old Swedish	svar	—
3	Old Norse	svárr	hard, heavy
4	Proto-Germanic	swēraz	heavy; grave, grievous, serious, important
5	Proto-Indo-European	swēr-	heavy

via Swedish morbror

Step	Language	Word	Meaning
1	Swedish	morbror	maternal uncle
2	Old Norse	móðurbróðir	—

Every word from Proto-Indo-European swēr- →Every word from Proto-Germanic swēraz →Every word from Old Norse svárr →