Where does “naztruo” come from?

naztruo (Esperanto) comes from Esperanto nazo, from German nase, from Middle High German nase, from Old High German nasa, from Proto-West Germanic *nasu, from Proto-Germanic nasō, from Proto-Indo-European nasō, from Proto-Indo-European néh₂s- — nose, nostril.

naztruo (Esperanto): nostril

Definitions

nostril

Ancestry of “naztruo”, step by step

naztruo traces back through two separate lines of ancestry.

via Esperanto nazo

Step	Language	Word	Meaning
1	Esperanto	nazo	nose
2	German	nase	nose
3	Middle High German	nase	nose
4	Old High German	nasa	nose
5	Proto-West Germanic	*nasu	nose
6	Proto-Germanic	nasō	nose
7	Proto-Indo-European	nasō	—
8	Proto-Indo-European	néh₂s-	nose, nostril

via Esperanto truo

Step	Language	Word	Meaning
1	Esperanto	truo	hole
2	French	trou	hole; blank; pause in conversation
3	Medieval Latin	traugus	—

Every word from Proto-Indo-European néh₂s- →Every word from Proto-Indo-European nasō →Every word from Proto-Germanic nasō →