18 Common Words That Have Unexpected Science Definitions

Many words in the English language that seem remarkably common have a surprising secondary definition known mostly to scientists in different disciplines. Here are 18 words drawn from the American Heritage Science Dictionary that have an alternative meaning in various science disciplines. Some may be familiar, and others less so. This refers not only the drooling nightmare that terrified Sigourney Weaver but also to non-native creatures and plant species introduced to an area from which they don't originate. When you've graduated from an institution of learning, you become an alumni or "alum," but the word is also the name of any various crystalline double salts of a trivalent metal (such as aluminum, chromium, or iron) or a monovalent metal (such as potassium or sodium).