Sentence:  What is not understood is the power hunger that resides in what the psychiatrist Kenneth Colby calls the "<WSD>wetware</WSD>"— the human brain about which we know very little except that it is composed of about 75 percent water. 
Meaning of the word marked with <WSD> tags:  The human brain or mind, often specifically as a computing element. Adapted as a biological parallel to hardware and software. Common in the cyberspace genre of science fiction.