Where does “pettömaito” come from?

pettömaito (Ingrian) comes from Finnish pettää, from Proto-Finnic pettädäk, from Proto-Baltic spenˀstei.

Ancestry of “pettömaito”, step by step

pettömaito traces back through two separate lines of ancestry.

via Finnish pettää

StepLanguageWordMeaning
1Finnishpettääto cheat, con, swindle, defraud; to deceive,...
2Proto-Finnicpettädäkto betray
3Proto-Balticspenˀstei—

via Ingrian maito

StepLanguageWordMeaning
1Ingrianmaitomilk
2Proto-Finnicmaitomilk
3Proto-Uralicmajδ̕ɜ—
Every word from Proto-Baltic spenˀstei →Every word from Proto-Finnic pettädäk →Every word from Finnish pettää →