Dys- is the Greek prefix for bad, and peptos is Greek for digested. Together they make the word dyspeptos, which means hard to digest or literally, badly digested. The Greek word became the root for the adjective dyspeptic, which in turn was the basis for dyspepsia. Sometimes people may say you have dyspepsia when they mean you are chronically in a bad mood or so irritable that it seems like you suffer from chronic indigestion — although this usage is more common with dyspeptic.