Almost everyone has encountered the problems of acronyms and other technical jargon. Those of us who teach or give public presentations learn to avoid most such specialized technical terms, or else to define them carefully. Somewhat less well understood is the problem of using familiar words in unfamiliar ways. Here the dangers of miscommunication are actually greater, because the listeners (or readers) may think they understand the term when they do not. It is relatively straightforward to ask questions or look up a word when someone uses jargon that we are not familiar with. More pernicious are situations where we think we are communicating but are not.