The word 'frenemy' was first used in 1953 to describe the relationship between Russia and America.

"Frenemy," sometimes spelled "frienemy,” is a combination of the words "friend" and "enemy." It can be used to describe an enemy pretending to be a friend, or it can describe a real friend with whom one is competing for something – a title, a job or popularity.

The word is not only used to describe personal relationships, but also refers to political and commercial relationships among individuals, groups, corporations and even countries. The word has appeared in print as early as 1953 when W. Winchell wrote: "Howz about calling the Russians our Frienemies?" In the ‘Nevada State Journal ‘ on 19 May 1953.

Although the word has been around for a long time, it was popularized on the third season of the television series ‘Sex and the City’. In politics one could say that the Arabic proverb, ‘The enemy of my enemy is my friend,’ comes into play and evolves into ‘frenemy’ when two countries that are not necessarily friends, work together against a common, more threatening enemy.

Frenemy has become a popular word and a widely used concept. It has been written about in publications such as ‘Businessweek’ and the topic appears abundantly on various websites like that of ‘Scientific American’ and on countless blog pages.

(Source)