Search: What's a word?

Hi,
online 'Technical Manual' exemplifies that run matches any of run, runs, runner, running, rundown, etc.
However, it doesn't state how corner cases are handled:
Stefan
online 'Technical Manual' exemplifies that run matches any of run, runs, runner, running, rundown, etc.
However, it doesn't state how corner cases are handled:
- what constitutes a word: obviously, a-z... but what about leading, embedded numbers, caps?
- what about special characters? I sometimes search program source code, with (), {}, ...
- words with embedded string run (eg. fastRun?)
- can any of that be enforced to match an adapted search string?
Stefan