(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

plural of index fossil

plural of index finger

(programming) The use of a negative integer as an array offset to access from the end of the array. Array[-3] accesses the 3ʳᵈ element from the end of the array, the same as Array[ArraySize - 3].