ambulacrum
noun
am·bu·la·crum ˌam-byə-ˈla-krəm 
-ˈlā-
plural ambulacra ˌam-byə-ˈla-krə
-ˈlā-
: an ambulacral area or part
Word History
Etymology
borrowed from New Latin ambulācrum, going back to Latin, "place for walking, promenade," from ambulāre "to walk, walk for pleasure or health" + -crum, suffix of instruments (dissimilated from *-clum, going back to *-tlom) — more at amble entry 1
First Known Use
1769, in the meaning defined above