vas·cu·lar / ˈvaskyələr/ • adj. Anat., Zool., & Med. of, relating to, affecting, or consisting of a vessel or vessels, esp. those that carry blood: vascular disease the vascular system. ∎ Bot. relating to or denoting the plant tissues (xylem and phloem) that conduct water, sap, and nutrients in flowering plants, ferns, and their relatives.DERIVATIVES: vas·cu·lar·i·ty / ˌvaskyəˈlaritē/ n.