The name Tuesday derives from the Old English "Tiwesdæg" and literally means "Tiw's Day". Tiw is the Old English form of the Proto-Germanic god *Tîwaz, or Týr in Norse, a god of war and law. *Tîwaz derives from the Proto-Indo-European base *dei-, *deyā-, *dīdyā-, meaning 'to shine', whence comes also such words as "deity".
The Latin name dies Martis ("day of Mars") is equivalent to the Greek ἡμέρα Ἄρεως. In most languages with Latin origins (French, Spanish, Catalan, Italian, Romanian, Galician, Sardinian, Corsican, but not Portuguese), the day is named after Mars, the Roman god of war.
In some Slavic languages the word Tuesday originated from Old Church Slavonic word въторъ meaning "the second" (Serbian: уторак (utorak)). Bulgarian and Russian "Вторник" (Vtornik) is derived from the Bulgarian and Russian adjective for 'Second' - "Втори" (Vtori) or "Второй" (Vtoroi)
In Japanese, the word Tuesday is 火曜日(ka youbi), meaning 'fire day' and is associated with 火星 (kasei): Mars (the planet), literally meaning "fire star". Similarly, in Korean the word Tuesday is 화요일 (hwa yo il), also meaning fire day.
In the Indo-Aryan languages Pali and Sanskrit, as well as in Thailand, the name of the day is taken from Angaraka ('one who is red in colour') a style (manner of address) for Mangal, the god of war, and for Mars, the red planet.