|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
|the offspring of a zebra and a donkey.|
endothelium en·do·the·li·um (ěn'dō-thē'lē-əm)
n. pl. en·do·the·li·a (-lē-ə)
A thin layer of flat epithelial cells that lines serous cavities, lymph vessels, and blood vessels.