1728, "secreting sebum;" 1783, "pertaining to tallow or fat;" from Latin sebaceus "of tallow," from sebum "tallow, grease" (see sebum). Meaning "oily, greasy, fatty" is from 1783.
Entries linking to sebaceous
sebum n.
"a secretion of the sebaceous glands," 1728, from medical use of Latin sebum "sebum, suet, grease," which is perhaps related to sapo "soap" (see soap (n.)), but de Vaan is skeptical and gives it no etymology.