Tīwesdæg

The Romans called it dies Martis, the day of Mars. Mars was the Roman god of war, second only to Jupiter in the pantheon, and the father of Romulus and Remus. His day fell third in the planetary week. French mardi, Spanish martes, Italian martedi -- Mars is still there in every Romance language.

When the Germanic peoples translated the Roman week into their own languages, they practiced what linguists call interpretatio germanica: matching Roman gods to their nearest Norse equivalents. For Mars, they chose Tiw (Old English) or Tyr (Old Norse), a one-handed god of war and justice. Tyr had lost his hand to the great wolf Fenrir, placing it in the beast's mouth as a pledge of good faith. The wolf bit it off. Tyr kept his word anyway.

The match was not perfect. Mars was a battlefield god, loud and aggressive. Tyr was quieter -- a god of oaths, legal proceedings, and the kind of courage that involves sacrifice rather than conquest. But both were warriors, and that was enough for a calendar slot. Old English Tiwesdaeg became Middle English Tewesday, then Tuesday.

Tiw faded from English memory almost completely. He has no surviving temples, no medieval legends, no comic book franchise. Thor got a Marvel series. Odin haunts half of fantasy literature. Tiw got a weekday and nothing else. He is the most invisible god in the English language -- present every seven days, recognized by almost no one.