Where does “spenu” come from?

spenu (Proto-West Germanic) comes from Proto-Germanic spenô, from Proto-Indo-European psten-os-, from Proto-Indo-European pstḗn, from Proto-Indo-European ph₂ǵ-sth₂-ḗn, from Proto-Indo-European steh₂- — to stand.

Ancestry of “spenu”, step by step

StepLanguageWordMeaning
1Proto-Germanicspenônipple
2Proto-Indo-Europeanpsten-os-
3Proto-Indo-Europeanpstḗnbreast, teat
4Proto-Indo-Europeanph₂ǵ-sth₂-ḗn
5Proto-Indo-Europeansteh₂-to stand
Every word from Proto-Indo-European steh₂-Every word from Proto-Indo-European ph₂ǵ-sth₂-ḗnEvery word from Proto-Indo-European pstḗn