Reaping is generally used to describe the action of terminating zombie processes, which are children that have outlived their parent. Since their parent does not exist to clean up after the child, the kernel's process table retains the defunct child. Such zombies must be reaped.

Killing a process is a more general term used to describe the act of terminating an active process.

If you are trying to automate the response to a dialog box, that's different. Just killing it could be bad.