Most familiar today as
奥运圣火 (Olympic flame) — lit at Olympia in Greece and carried to the host city in the torch relay (
圣火传递, shènghuǒ chuándì). The phrase also covers altar-fires in religious contexts (Zoroastrian, etc.).
圣 ('sacred/holy') is the same character as in
圣经 (Bible) and
圣诞 (Christmas).