As Zack said, it means endless dream. But 'owarinai yume' is correct. There are a few possible forms. 'owara-nai yume' (a dream that doesn't finish). In this case, owara-nai is the negative form of owaru(a verb for finish). 'owari nai yume' (a dream that doesn't have an end). In this case, owari nai is the negative form of owari aru. owari is a noun that means an end.

It means endless dream, but the word should be owaranai