WordNet (r) 3.0 (2006):

grunge
    n 1: the state of being covered with unclean things [syn:
         dirt, filth, grime, soil, stain, grease,
         grunge]

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

grunge
 /gruhnj/, n.

    1. That which is grungy, or that which makes it so.

    2. [Cambridge] Code which is inaccessible due to changes in other parts of
    the program. The preferred term in North America is dead code.


The Free On-line Dictionary of Computing (30 December 2018):

grunge

   /gruhnj/ 1. That which is grungy, or that which makes it so.

   2. [Cambridge] Code which is inaccessible due to changes in
   other parts of the program.  The preferred term in North
   America is dead code.