...and immortal blood came flowing quickly from the goddess, the ichor that courses through their veins, the blessed gods- they eat no bread, they drink no shining wine, and so the gods are bloodless, and so we call them deathless.
-Fagles' translation of Homer's
The Iliad, Book 5 v. 381-384
Ichor is God's blood in Greek myth, originating from the substance that was their sustenance; golden nectar, divine ambrosia.
Since "lichor" is the substance found from a plant in Mankar's ethereal paradise, tellingly named "Mana bloom", it probably refers to something similar.