If you have a compiler that supports C99 you can
Otherwise, you can define your own if you'd like. Depending on how you want to use it (and whether you want to be able to compile your code as C++), your implementation could be as simple as:
#define bool int
#define true 1
#define false 0
In my opinion, though, you may as well just use
int and use zero to mean false and nonzero to mean true. That's how it's usually done in C.