noun1. a grasslike cyperaceous marsh plant, Scirpus lacustris, used for making mats, chair seats, etc
 2.   a popular name for reed mace (sense 1)
3.   a biblical word for papyrus (sense 1) 
 Word origin
C15 
bulrish, bul- perhaps from 
bull1 + 
rish rush2, referring to the largeness of the plant; sense 2 derived from the famous paintingby Sir Lawrence 
Alma-Tadema (1836–1912), Dutch-born English painter, of the finding of the infant Moses in the"bulrushes" — actually reed mace