Where does “ἔκζεμα” come from?

ἔκζεμα (Ancient Greek) comes from Ancient Greek ζέμα, from Ancient Greek ζέω, from Proto-Indo-European yes- — to foam; to boil.

ἔκζεμα (Ancient Greek): cutaneous eruption, an eczema

Definitions

ἔκζεμα traces back through 3 separate lines of ancestry.

Step	Language	Word	Meaning
1	Ancient Greek	ζέμα	fermentation, boiling
2	Ancient Greek	ζέω	to boil, seethe, bubble; to heat
3	Proto-Indo-European	yes-	to foam; to boil

Step	Language	Word	Meaning
1	Ancient Greek	ἐκ	Out of, from; from, with the source of; to denote...
2	Proto-Hellenic	*eks	—

Step	Language	Word	Meaning
1	Ancient Greek	ἐκζέω	To boil out or over; to break out; To be boiled...
2	Ancient Greek	ἐκ-	With a sense of removal: out, away, off;...