WordNet sense 1 (at or near the north pole):

arctic, north-polar

WordNet sense 2 (characterized by opposite extremes; completely opposed):

diametric, diametrical, opposite

WordNet sense 3 (unlike in nature or quality or form or degree):

different

WordNet sense 4 (extremely cold):

frigid, gelid, glacial, icy

WordNet sense 5 (used of physical coldness; having a low or inadequate temperature or feeling a sensation of coldness or having been made cold by e.g. ice or refrigeration):

cold

WordNet sense 6 (being of crucial importance):

pivotal

WordNet sense 7 (of extreme importance; vital to the resolution of a crisis):

crucial, important

WordNet sense 8 (of a particle or body or system; having a net amount of positive or negative electric charge):

charged