What does "charlock" mean?

Charlock: A cruciferous plant (Brassica sinapistrum) with yellow flowers; wild mustard. It is troublesome in grain fields. Called also chardock, chardlock, chedlock, and kedlock. Jointed charlock, White charlock, a troublesome weed (Raphanus Raphanistrum) with straw- colored, whitish, or purplish flowers, and jointed pods: wild radish.