Where does “hjärnsläpp” come from?

hjärnsläpp (Swedish) comes from Swedish hjärna, from Old Norse hjarni, from Proto-Germanic hersô, from Proto-Indo-European ḱerh₂s-, from Proto-Indo-European ḱerh₂- — head, top; horn.

hjärnsläpp (Swedish): a temporary (severe) loss of judgment or thinking ability, a "braino"

Definitions

a temporary (severe) loss of judgment or thinking ability, a "braino"

Ancestry of “hjärnsläpp”, step by step

hjärnsläpp traces back through two separate lines of ancestry.

via Swedish hjärna

Step	Language	Word	Meaning
1	Swedish	hjärna	a brain; a brain; someone who provides the...
2	Old Norse	hjarni	the brain
3	Proto-Germanic	hersô	crown of head
4	Proto-Indo-European	ḱerh₂s-	head; hornet
5	Proto-Indo-European	ḱerh₂-	head, top; horn

via Swedish slapp

Step	Language	Word	Meaning
1	Swedish	slapp	completely relaxed; lazy; not tense, like old...
2	Old Norse	slápr	—
3	Proto-Germanic	slap-	—
4	Proto-Indo-European	(s)leh₂b-	to hang loosely, be weak; to be weak, limp,...

Every word from Proto-Indo-European ḱerh₂- →Every word from Proto-Indo-European ḱerh₂s- →Every word from Proto-Germanic hersô →