1.NounA unit (equal to one "ordinary" degree) used to measure the piston travel (position) e.g. to adjust ignition. When the piston is at its highest point, known as the top dead center (TDC), the crankshaft angle (crank angle) is at 0 crank angle degrees (CAD).
"The exhaust valve opening is selectively varied to begin at about 160 or more crank angle degrees past top dead center.(www.freepatentsonline.com)"