1.Definition: being of crucial importance

"The polar events of this study", "A polar principal"

Related Adjective(s):pivotal

2.Definition: characterized by opposite extremes; completely opposed

"Extreme and indefensible polar positions"

Related Adjective(s):diametric, diametrical, opposite

3.Definition: extremely cold

"Polar weather"

Related Adjective(s):arctic, frigid, gelid, glacial, icy

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

"Polar regions"