Well, it's why we have language. If we used the same word for every subject, e.g., "I drove my pick down to the pick so that I could buy some picks to bring back to my pick, and then my family could sit down to eat pick", you'd probably be able to figure out what I meant, but it's a helluva lot more mental energy to translate. Yes, it's confusing to use the word "flat" to mean lowered in pitch as well as smooth and even without marked lumps or indentations but although they are same word, they should not be iterated the same way. A note is not squashed down to a different shape; it is lowered innpitc, therefore flatted.