ἰχώρ

In Book 5 of the Iliad, the hero Diomedes wounds Aphrodite with a spear. Homer describes what flows from the goddess: ichor, such as flows in the veins of the blessed gods, for they eat no bread and drink no gleaming wine, and thus they have no blood. The word appears at one of the most peculiar moments in Greek literature, where a mortal man draws divine substance from an immortal body. Homer was careful: this fluid was specifically what distinguished gods from humans, the visible sign of a different biology.

The word's origins are uncertain, possibly from a Proto-Indo-European root meaning moisture or flow, though ancient scholars proposed various theories. Medical writers beginning with Hippocrates in the 5th century BCE borrowed ichor for a different purpose: the thin, watery fluid that seeps from infected wounds. The shift is striking. The same word carries divine substance in Homer and pathological discharge in a physician's case notes, and neither use drove out the other.

Latin adopted the word as ichor without changing it, and Roman medical writers including Galen in the 2nd century CE used it as a standard term for thin, serous wound discharge. Medieval medical manuscripts in Latin kept the word in regular use, and it passed into early modern English through the translation of Greek and Roman medical texts during the 16th-century Renaissance. The Oxford English Dictionary records English ichor by 1638, initially in medical writing. The divine meaning arrived slightly later, when classical scholars and poets began citing Homer's Iliad in English.

By the 19th century, ichor lived in two worlds simultaneously: surgeons used it for watery discharge from ulcers, while poets and mythographers used it for divine blood in classical allusions. Edgar Allan Poe used the word in The Fall of the House of Usher in 1839 to describe something supernatural seeping through stone walls. The Gothic literary tradition seized ichor as a name for ambiguous fluid, something neither blood nor water, belonging to another order of being entirely. H.P. Lovecraft carried this use into the 20th century, and the word has been a staple of horror and fantasy ever since.