It's pronouced "da-men-ta-tive", but I don't know how to spell it and i must be way off because I can't find it either. Help me out.
Are you thinking of the word "diminutive", which means very small or unusually small? What is the meaning of the word you are trying to use?
I guess there are many words out there that look different than they sound. There's a state like that- Connecticut. It "sounds" like "kaneticut", and "looks" like "Connect-a-cut".