Noah, as one pronounces the name in English, is pronounced, in Hebrew, No'ach. The Bible was written originally in Hebrew.
[The "ach" in No'ach is pronounced like the German "Ach!" (Ach du lieber! Achtung!) or like the guttural sound in the Scottish word for lake, "loch."]
Noahide means "human," basically. All of us descend from Noah ("No'ach.") Humankind is just one family. As the Bible tells the story, Noah and his wife Na'amah are the ancestors of us all.
The People of Israel constitute a Noahide tribe, but usually "Noahide" refers to non-Jews, the vast majority of the human race - to the more than 99.80% of humankind which isn't Jewish.
[Another word for Noahide is Noahite. Some very old reference books also refer to Noahides as Noachians.]
