A disorder which can be anything from sucking on wool or objects to ingesting non food items.  This can be a very serious condition as the objects ingested can cause serious internal harm such as irratation, blockage, among other gastro intestinal problems such as twisted intestines, telescoping intestines, intestinal rupture, bleeding and death.

http://www.vetmedcenter.com/Consumer/display.asp?id=8466&dt=p

http://www.21cats.org/health.html#2
scroll down right hand side to Pica.....