Floridaâs tract of coral reefs has the honor of being the third-largest barrier reef ecosystem in the world. However, it could soon be a thing of the past, as the acidification of the oceanâs water is dissolving it faster than it can rebuild.
index (plural indexes or indices) 1  An alphabetical listing of items and their location. The index of a book lists words or expressions and the pages of the book upon which they are to be found. 2  The index finger; the forefinger. 3  A movable finger on a gauge, scale, etc.
A stock index is a measure of the overall performance of a stock market, based on a group of stocks that are meant to represent the market as a whole. The Dow Jones Industrial Average, or Dow, is one of the most common stock indexes used to gauge the performance of the U.S. stock market.