The question is probably "What is a prefix?". A prefix is the first part of a word that changes the word's meaning. For example, "uninterested" in this word "un" is the prefix and "un" means "not". Also, "indescribable", "in" is the prefix and "in" means "not" as well. One more: "inflammable", "in" is the prefix again. However, this "in" means "is" (inflammable = is flammable).