A prefix is a letter or a group of letters that appears at the beginning of a word and changes the word’s original meaning. Prefixes can, for example, create a new word opposite in meaning to the word the prefix is attached to. They can also make a word negative or express relations of time, place or manner.
The origins of words are extremely complicated. You should use this list as a guide only, to help you understand possible meanings. But be very careful, because often what appears to be a prefix is not a prefix at all.