Any ancient remains of a plant or animal that lived during a specific geological period and that can be used to date the containing rocks.

(physics) The ratio of the speed of light in air or vacuum to that in another medium.

(information science) An indexing algorithm which indexes a document based on the keywords being searched for.

(finance) A Japanese stock market index; normally refers to the Nikkei 225, which is calculated by aggregating the share prices of 225 large Japanese companies quoted on the Tokyo Stock Exchange, and thus reflects the performance of major Japanese businesses.

(economics) A statistical estimate of the level of prices of some class of goods or services.

A piece of heavy paper stock used to record information to be stored in an index.

(information science) A term that captures the essence of the topic of a document, used as keyword to retrieve documents in an information system, for instance a catalog or a search engine.

(information science) The act of describing a document by index terms to indicate what the document is about or to summarize its content, the index terms often coming from a controlled vocabulary.

(transitive) To index (something) using index cards.

plural of index card