What was the name given to the nations fighting against central powers?

They were called the Allies:

The two opposing groups that fought in World War I were the Central Powers (Germany, Austria-Hungary, Bulgaria, and Turkey) and the Allies, an alliance that grew from the three members of the Triple Entente (Britain and the British Empire, France, and Russia) to incorporate 27 Allied and Associated powers, including Italy and, towards the end of the war, the USA.