There is no day of the week that directly means "God of War." Otherwise the name of that day would be indeed "God of War." However, there is Tuesday and Wednesday, or rather, Tyr's Daeg, and Woden's Daeg, in the old norse, from which our modern names for the days of the week come from.
Tyr is the God of justice through battle, and honor. Woden is (among other things) the God of battle for greedy ends, and bloodshed.
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2nd Answer:
Tuesday is originally named after Mars, the god of war.
Tuesday was called Martis, but was changed when the christian faith dominated.
For more information of days and their orgins:
http://www.friesian.com/week.htm
Saturday: Day of Saturn, the Roman God Saturn. (Saturn's Day)
The phrase "sabbath day"comes from the Bible. Sabbath means "to rest" and the sabbath day was instituted by God during creation week when He created the seventh day and made it a holy day for rest. God also included the sabbath day into the ten commandments.
This day is named after the Norse god Tyr, or Thor, who was synonymous with the Roman god Mars, god of war.
It was named after the Norse god Tyr, Tiwesdæg, meaning, Tyr's day. He was associated with single combat and pledges. Tuesday in Latin, is Dies Martis. Meaning, day of Mars, the Roman war god.
from Wikipedia : 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 t-r-2inNorse, a god of war and law.
Thursday. Originally "Thor's Day"
Tuesday means Tyr's Day. Tyr was the Norse god of war, equivalent to the Roman Mars and Greek Ares. In Latin and the Romance and Celtic languages Tuesday is named for the god of war. ("Martis dies" which means"Mars' Day" in Latin, "martes" in Spanish, dé máirt in Irish, etc.) So in the broadest sense, Tuesday means "the day of the war god."
Tuesday was named for Tyr, who was a Norse god of war. Odin, or Woden, was also considered a god of war - Wednesday was named for him.
The word Tuesday originates from the Middle English word Tewesday. It means Tiw's Day and is named after the Norse god Tiw, also called Tyr, who was the god single combat and glory.
The real spelling of the fourth day of the week is "Wednesday". It is derived from Old English "Wōdnesdæg" which means "day of Woden", referring to the Norse god Odin.
Saturday: Day of Saturn, the Roman God Saturn. (Saturn's Day)
Sunday is the day to worship God. You should really worship God all days of the week.
The third day of the week which is Tuesday.
MON means Monday, which is the second day of the week.
Thursday
Thursday is named after the Norse God of Thunder, Thor. It is derived from the Old English word "Þūnresdæg," which means Thor's Day.
Saturday