Prefixes are letters that we add to the beginning of a word to make a new word with a different 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. Here are some examples:
base word
possible
able
payment
war
terrestrial
cook
prefixed word
impossible
unable
non-payment
pre-war
extraterrestrial
overcook
type of meaning
opposite
opposite/negation
negation
time (before)
place (outside of/beyond)
manner (too much)