From Jargon File (4.4.4, 14 Aug 2003) [jargon]:
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).