Answer:
\bcat\w*
\bcat\w*
Here is a table of boundary matchers:
| Matches | |
|---|---|
^ | Beginning of a line |
$ | End of a line |
\b | word boundary |
\B | non-word boundary |
The last four of these only make sense when searching for substrings in a textfile of possibly many lines.
(Trick Question: ) What character ends a line?