adjective

reaching a high or the highest degree; very great.

extreme cold

utmost,uttermost,very great,greatest,greatest possible,maximum,maximal,highest,ultimate,supreme,paramount,great,acute,major,intense,enormous,severe,high,superlative,exceptional,extraordinary

noun

either of two abstract things that are as different from each other as possible.

we represented opposite extremes of college society—he a member of the Old Guard, I one of the radicals

opposite,antithesis,(other) side of the coin,(opposite) pole,contrary,(exclusive) alternative,opposing pair,antipode