Regex - Find all matching words that that don't begin with a specific prefix

Question

How would I construct a regular expression to find all words that end in a string but don\'t begin with a string?

e.g. Find all words that end in \'friend\' that don

Answer 1

I changed Rob Raisch's answer to a regexp that finds words Containing a specific substring, but not also containing a different specific substring

\b(?![\w_]*Unwanted[\w_]*)[\w_]*Desired[\w_]*\b

So for example \b(?![\w_]*mon[\w_]*)[\w_]*day[\w_]*\b will find every word with "day" (eg day , tuesday , daywalker ) in it, except if it also contains "mon" (eg monday)

Maybe useful for someone.