1 - A philosophy about music started in the later 1800's by supposed father of industrial music Luigi Russolo. The first recorded piece being "Corale" in 1921 by Luigi and his brother Antonio. The philosophy included using means other than the traditional means of creating music. With such devices as intonarumori, or noise machines.
2 - A short lived genre revived from a philosophy by Throbbing Gristle and continued by bands such as Einsturzende Neubauten, Laibach and Skinny Puppy.
3 - A term wrongly used to identify electronic and electronic rock music. Fits in with terms like techno and electronica. Industrial rock evolved out of this.
4 - Word associated with electronic music because of the artificial way it is made.
5 - Music beyond music.
That can't be industrial! They used traditional instruments. Not an experimental instrument to be found!