When do you personally start counting something as a "word"? What is the 'official' way?

C's first were pretty clear- mama, dada, dog (da!). Now she has been saying the same sound back to is after we say Thank You, kind of sounds like geh-geh. It's consistently used to say thank you, but doesn't sound like thank you.

Either way it's adorable, but wondering when other people count "words".