WordNet (r) 3.0 (2006):

rockcress
    n 1: noxious cress with yellow flowers; sometimes placed in
         genus Sisymbrium [syn: yellow rocket, rockcress,
         rocket cress, Barbarea vulgaris, Sisymbrium barbarea]
    2: any of several rock-loving cresses of the genus Arabis [syn:
       rock cress, rockcress]