corrugated
ˈkɒrəɡeɪtɪd
adjective
(of a material or surface) shaped into a series of parallel ridges and grooves so as to give added rigidity and strength.
corrugated cardboard
ridged,fluted,channelled,furrowed,grooved,crimped,folded,crinkled,crinkly,puckered,creased,wrinkled,wrinkly,crumpled,rumpled,striate,striated