7.3.3 - Difficult Terrain Type
Core Rules, p. 18
Some terrain may be labelled as Difficult terrain by various effects or players may agree to treat certain terrain as Difficult terrain during setup. Any area of Difficult terrain should be clearly defined between you and your opponent. When a model moves through, would end on, or begins in difficult terrain, it subtracts -2" to its Movement (M) characteristic. Any charge through difficult terrain is considered a disordered charge (see 11.1). Some specific units may be forced to take a Dangerous Terrain test (See 7.3.5) in addition from moving through Difficult terrain.