index

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Something that serves to guide, point out, or otherwise facilitate reference, especially.
• noun An alphabetized list of names, places, and subjects treated in a printed work, giving the page or pages on which each item is mentioned.
• noun A thumb index.
• noun A table, file, or catalog.
• noun Computers A list of keywords associated with a record or document, used especially as an aid in searching for information.
• noun Something that reveals or indicates; a sign.
• noun A character (☞) used in printing to call attention to a particular paragraph or section.
• noun An indicator or pointer, as on a scientific instrument.
• noun Mathematics A number or symbol, often written as a subscript or superscript to a mathematical expression, that indicates an operation to be performed, an ordering relation, or a use of the associated expression.
• noun A number derived from a formula, used to characterize a set of data.
• noun A statistical value that represents the price or value of an aggregate of goods, services, wages, or other measurable quantities in comparison with a reference number for a previous period of time.
• noun A number that represents the change in price or value of stocks or other securities in a particular market, sector, or asset class.
• noun The stocks or other securities represented by an index.
• noun Roman Catholic Church A list formerly published by Church authority, restricting or forbidding the reading of certain books.
• transitive verb To furnish with an index.
• transitive verb To enter in an index.
• transitive verb To indicate or signal.
• transitive verb To adjust through indexation.

from The Century Dictionary.

• noun That which points out; anything that shows, indicates, or manifests.
• noun In logic, a sign which signifies its object by virtue of being really connected with it.
• noun Something intended to point out, guide, or direct, as the hand of a clock or a steam-gage, the style of a sun-dial, an arm of a guide-post, or the figure of a hand .
• noun A detailed alphabetic (or, rarely, classified) list or table of the topics, names of persons, places, etc., treated or mentioned in a book or a series of books, pointing out their exact positions in the volume.
• noun Prelude; prologue.
• noun In anatomy, the forefinger or pointing finger.
• noun In ornithology, the principal or middle digit of the wing of a bird: so called by those who hold that it is homologous with the forefinger of a mammal; by those who hold that the middle digit of the wing is the middle digit of a mammal, the pollex or thumb of a bird's wing is called the index.
• noun In mathematics, the figure or letter which shows to what power a quantity is involved; the exponent.
• noun In crystallography, in the notation of Whewell and Miller, one of three whole numbers which define the position of a face of a crystal: in the notation of Bravais, four numbers constitute the indices of a face of a hexagonal crystal.
• noun In musical notation, a direct.
• noun [capitalized] Same as Index Expurgatorius.
• noun See craniometry.
• To point out, as an index; indicate.
• To make an index to, or place in an index: as, to index a book, or the contents of a book.
• noun In instruments having graduated circles for angular measurement, the pointer or mark on the movable arm which is so placed as to move in close proximity to the graduated circle and thus to indicate the angle passed over between any two given positions of the arm; also, the arm or revolving member pivoted at the center of the graduated circle, which carries the index-mark or pointer.
• noun The numerical value of a measured object or process, or of a counted phenomenon, expressed in percentage of another measured object, or process, or counted phenomenon: applied particularly in measurements of organisms for expressing the ratio between the sizes of two organs. See craniometry.
• noun In forestry, the highest average actually found upon a given locality.
• noun Same as palatomaxillary or palatoalveolar index. Turner.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To provide with an index or table of references; to put into an index.
• transitive verb (Economics) To adjust (wages, prices, taxes, etc.) automatically so as to compensate for changes in prices, usually as measured by the consumer price index or other economic measure. Its purpose is usually to copensate for inflation.
• transitive verb To insert (a word, name, file folder, etc.) into an index or into an indexed arrangement.
• noun That which points out; that which shows, indicates, manifests, or discloses.
• noun (printing) That which guides, points out, informs, or directs; a pointer or a hand that directs to anything, as the hand of a watch, a movable finger or other form of pointer on a gauge, scale, or other graduated instrument.
• noun A table for facilitating reference to topics, names, and the like, in a book, usually giving the page on which a particular word or topic may be found; -- usually alphabetical in arrangement, and printed at the end of the volume. Typically found only in non-fiction books.
• noun obsolete A prologue indicating what follows.
• noun (Anat.) The second finger, that next to the pollex (thumb), in the manus, or hand; the forefinger; index finger.
• noun (Math.) The figure or letter which shows the power or root of a quantity; the exponent.
• noun The ratio, or formula expressing the ratio, of one dimension of a thing to another dimension.
• noun A number providing a measure of some quantity derived by a formula, usually a form of averaging, from multiple quantities; -- used mostly in economics. See, for example, the consumer price index.