You may need
(?<!prefix )word
(and maybe take care of the spaces).
(?!)
is a negative lookahead but in your case you need a negative lookbehind (i.e. (?<!)
).
You may need
(?<!prefix )word
(and maybe take care of the spaces).
(?!)
is a negative lookahead but in your case you need a negative lookbehind (i.e. (?<!)
).