1.Definition: being of crucial importance
"The polar events of this study", "A polar principal"
2.Definition: characterized by opposite extremes; completely opposed
"Extreme and indefensible polar positions"
4.Definition: having a pair of equal and opposite charges
5.Definition: located at or near or coming from the earth's poles
"Polar diameter", "Polar zone", "A polar air mass", "Antarctica is the only polar continent"
6.Definition: of or existing at or near a geographical pole or within the Arctic or Antarctic Circles