What is ichor (from The Iliad)?

In Greek mythology, golden-colored ichor is the ethereal fluid flowing through the veins of the immortal gods. (But these days, you don't need to be a Greek god to produce ichor. It's also the name of the thin, acrid, watery stuff that discharges from a wound, ulcer, or sore.)

Although the Greek gods were immortal, they could still be injured or suffer pain. In Book V of Homer's Iliad, a huge battle — the siege of Troy — takes place. Diomedes wounds Aeneas (the son of the goddess Aphrodite) and is about to finish him off when Aphrodite rushes in to protect her son. Enraged at Aphrodite's interference, Diomedes pursues and wounds her:

He gouged her just where the wristbone joins the palm
and immortal blood came flowing quickly from the goddess,
the ichor that courses through their veins . . .