Except non is not an english word, it is a prefix of latin origin. Which is why american style manuals will always ask you to merge it with the subsequent word, without a hyphen. British rules differ, and รขโฌยฆ To record and summarize the discussion in the comments, while the oed mostly uses the hyphen, many other dictionaries don't, and the ngrams show higher non-hyphenated usage than hyphenated.
Non Nude Panty Teens - News Update
Except non is not an english word, it is a prefix of latin origin.