In How to write mathematics, P. R. Halmos has an amusing anecdote:
I once studied certain transformations called "measure-preserving". (Note the hyphen: it plays an important role, by making a single word, an adjective, out of two words.) Some transformations pertinent to that study failed to deserve the name; their failure was indicated, of course, by the prefix "non". After a long sequence of misunderstood instructions, the printed version spoke of a "nonmeasure preserving transformation". That is nonsense, of course, amusing nonsense, but, as such, it is distracting and confusing nonsense.
As a nonnative english speaker I wonder: What version would have been correct? I guess it is either "non-measure-preserving", "nonmeasure-preserving" or "non measure-preserving". The last one feels a bit odd to me, I think "not measure-preserving" would be better in that case?