How can I use Finder's search feature to find all files that do not match a certain criteria?
For instance, all files that don't end in ".txt" in the current folder.
Just typing the operand NOT before the criteria will do the trick.
So, in this case, typing NOT .txt
will show all the files but the ones with the .txt extension.
Name > Matches > NOT "two words"
Exclude search results by using the '-' symbol
like this: Name -GMT
Will display filenames that don't include '-GMT'