The prefix meaning 'OUTSIDE' can be found in three and four letter words. The three letter word is ECT, which is derived from the Greek ektos, meaning OUTSIDE. The four letter word is EXO, which is derived from the Greek exo, meaning OUTSIDE or beyond. The last word is ECTO, which is a combination of the two Greek words ektos and exo, meaning OUTSIDE and beyond. All three words are used to describe something that is located OUTSIDE or beyond the normal range.