Vernix caseosa: A white cheesy substance that covers and protects the skin of the fetus and is still all over the skin of a baby at birth. Vernix caseosa is composed of sebum (the oil of the skin) and cells that have sloughed off the fetus' skin.
"Vernix" is the Latin word for "varnish." The vernix varnishes the baby. "Caseosa" is "cheese" in Latin.
