You can not say мечт, this is definetely incorrect. Word мечтаниe has a slightly different meaning, it's dreaming in English and it's more about the process of thinking of your dream. So there is no genitive plural of мечта in Russian, but you can say that using another word - Это одно из моих желаний, this phrase has exactly the same meaning.

You can not say мечт; this is definetely incorrect. The word мечтаниe has a slightly different meaning: it's dreaming in English and it's more about the process of thinking of your dream. So there is no genitive plural of мечта in Russian, but you can say that using another word - Это одно из моих желаний. This phrase has exactly the same meaning.