noun

• (typography) A symbol resembling a pointing hand, used to direct particular attention to a note or paragraph.
• (linguistics) A type of noun where the meaning of the form changes with respect to the context; e.g., 'Today's newspaper' is an indexical form since its referent will differ depending on the context. See also icon and symbol.
• (economics) A single number calculated from an array of prices or of quantities.
• (sciences) A number representing a property or ratio; a coefficient.
  "In other words, we predict that the index for a new pair of materials can be obtained from the indexes of the individual materials, both against air or against vacuum."

verb

• (transitive) To arrange an index for something, especially a long text.
  "MySQL does not index short words and common words."
• (chiefly economics) To normalise in order to account for inflation; to correct for inflation by linking to a price index in order to maintain real levels.
• (linguistics, transitive) To be indexical for (some situation or state of affairs); to indicate.
  "For example, the feature I indexes the current speaker in the speech event and you, the current addressee."
• (computing) To access a value in a data container by an index.