early 13c., "failure, failure to act," from O.Fr. defaute (12c.) "fault, defect, failure, culpability, lack, privation," from V.L. *defallita "a deficiency or failure," pp. of *defallere, from L. de- "away" + fallere "to deceive, to cheat; to put wrong, to lead astray, cause to be mistaken; to escape notice of, be concealed from." The financial sense is first recorded 1858; the computing sense is from 1966.
data A value or thing to use when none is specified by the user. Defaults are important for making systems behave in a predictable way without the user having to give lots of "obvious" details. For example: the default TCP/IP port for the HTTPprotocol is 80, the Unixls command does not list files whose names begin with ".", the default number base in most contexts is 10 (decimal), the default filename extension for Microsoft Word documents is ".doc". (2009-02-20)