It seems like there might be a typo in your question, but assuming you meant "prefix," a prefix is a group of letters added before a word to change its meaning. It can alter the word's tense, form a new word, or create a word with the opposite meaning.
Septagonal is the only one that I can think of.
That's a prefix used to multiply a unit by some power of 10 - most of them by a power of 1000. For example, milli = 1/1000, micro = 1/1,000,000, kilo = 1000, and Mega = 1,000,000.