Where does “oljeskifer” come from?

oljeskifer (Norwegian Bokmål) comes from Norwegian Bokmål olje, from Latin oleum, from Ancient Greek ἔλαιον, from Ancient Greek ἐλαία, from Proto-Hellenic elaíwā, from Proto-Indo-European loiwom.

oljeskifer (Norwegian Bokmål): oil shale

Definitions

oil shale

Ancestry of “oljeskifer”, step by step

oljeskifer traces back through two separate lines of ancestry.

via Norwegian Bokmål olje

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

via Norwegian Bokmål skifer

Step	Language	Word	Meaning
1	Norwegian Bokmål	skifer	schist, shale, slate
2	German	Schiefer	shale, slate; small splinter
3	Middle High German	schiver	—
4	Old High German	skivaro	—

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