A defunct process is a child process tha tlost its parent. You shouldn't have any defunct processes. Try to find out what is causing this to happen. Something isn't terminating correctly. You might need to install some patches or somehting, but defunct processes although seemingly harmless meana that something isn't terminating properly. defunct processes can also take up resources as they are still in the porcess table, the owner of the processes many times becomes init, which is the "godfather" o the process table.