Where does “armhule” come from?

armhule (Norwegian Bokmål) comes from Norwegian Bokmål arm, from Old Norse armr, from Proto-Germanic armaz, from Proto-Indo-European h₂ermos, from Proto-Indo-European h₂er- — to fit, to fix, to put together.

armhule (Norwegian Bokmål): an armpit

Definitions

an armpit

Ancestry of “armhule”, step by step

armhule traces back through two separate lines of ancestry.

via Norwegian Bokmål arm

Step	Language	Word	Meaning
1	Norwegian Bokmål	arm	poor; an arm
2	Old Norse	armr	arm; poor, unhappy; wretched, wicked
3	Proto-Germanic	armaz	arm; poor, miserable; pitiful, pitiable
4	Proto-Indo-European	h₂ermos	—
5	Proto-Indo-European	h₂er-	to fit, to fix, to put together

via Norwegian Bokmål hule

Step	Language	Word	Meaning
1	Norwegian Bokmål	hule	inflection of hul: ## definite singular ##...
2	Old Norse	hola	cave; to hollow
3	Old Norse	holr	hollow
4	Proto-Germanic	hulaz	hollow
5	Proto-Indo-European	ḱel-	to cover; to incline

Every word from Proto-Indo-European h₂er- →Every word from Proto-Indo-European h₂ermos →Every word from Proto-Germanic armaz →