what constitutes a "word"?

[fredly]

My 17m old daughter's only word is "daddy". Apart from that she says onomatopae, like miaou for the cat. I was wondering, just out of interest, if these can be considered as real words. They refer to specific 'objects', she uses them in the right context, so they obviously mean something for her. Would you agree?
And no, I'm not desperately trying to boast about the extent for her vocabulary by making it wider than it is

I'd say if you know what she means it's a word

ds is 18m and the only intelligible word he overuses is mama :)

she obviously knows what they mean!!my dd is 19months,and she chatters away to herself constantly.shes been calling my other dd coco for months now,you ask her where coco is and she'll shout and point to a picture if shes not in the room!!she did only say daddy for ages,but a couple of weeks ago 'mammy' popped out!