The Jargon File (version 4.4.7, 29 Dec 2003):

hardcoded
 adj.

    1. [common] Said of data inserted directly into a program, where it cannot
    be easily modified, as opposed to data in some profile, resource (see 
    de-rezz sense 2), or environment variable that a user or hacker can
    easily modify.

    2. In C, this is esp. applied to use of a literal instead of a #define
    macro (see magic number).