Where does “petrulka” come from?

petrulka (Polish) comes from Polish petroleum, from Medieval Latin petroleum, from Latin oleum, from Ancient Greek ἔλαιον, from Ancient Greek ἐλαία, from Proto-Hellenic elaíwā, from Proto-Indo-European loiwom.

Ancestry of “petrulka”, step by step

Step	Language	Word	Meaning
1	Polish	petroleum	—
2	Medieval Latin	petroleum	—
3	Latin	oleum	olive oil; the palaestra
4	Ancient Greek	ἔλαιον	olive oil, commonly used as an anointing oil; any...
5	Ancient Greek	ἐλαία	olive tree; olive; naevus
6	Proto-Hellenic	elaíwā	—
7	Proto-Indo-European	loiwom	—

Every word from Proto-Indo-European loiwom →Every word from Proto-Hellenic elaíwā →Every word from Ancient Greek ἐλαία →