The term 'polar opposites' refers to two opposite ends of a spectrum. In this case, the crossword solutions for the term are 'icecaps' (7 letters) and 'EXTREMES' (8 letters). Icecaps are large masses of ice that form at the poles of the Earth, while EXTREMES refer to the most extreme points on a scale. Both terms can be used to describe the concept of polar opposites, as they represent the two opposite ends of a spectrum.