Babies first words

I really don't know what is considered a first word. Is it when the first sounds are put together, or when the sounds/words are repeated, or when there is recognition with those words? Ellie is jabbering away, she has never been a silent baby, but now is really is not silent (even when she has her pacifier in her mouth).

Here are a few of her "first" words in the order she said them

dada- of couse this was her first word, and the one she says it the most often. This is a word that she says a lot when she is very happy

ee- this is definately her response when she sees or is near Chloe. She loves Chloe very much and likes it when she is near her (even though Chloe does not feel the same way).

yiyi- I really do not know what she is trying to say here, but for about a week she said it a lot. She does not say it much but when she does it goes on for a while.

mama- I couldn't wait until she said mama, but now I am not so such I like it. She only says mama when she is mad or wants something. Most of the time she is throwing a fit when she says mama.

bye-bye- she does not say this often, but it is starting to become more often.