Suint, also known as "wool grease" and "wool fat", is the purified form of the yellowish oil on new wool. In its pure, pale white form (produced by boiling, filtering, and sunning) it was used as a liniment in ancient times, and formed the base of a great many medicinal ointments in the ancient world. Modern lanolin is essentially the same substance in a highly purified form and remains in widespread use.
Pliny the Elder considers wool one of the two prime substances useful in home remedies (the other is eggs). Many of those he lists involve not wool grease but wool itself, mixed with various things and placed on (or inside) the affected part of the body. He says,
"The old Romans assigned to wool even supernatural powers, for they bade brides touch with it the doorposts of their new homes..." Natural HistoryXXIX:ix:33, translated by W. H.S. Jones, Loeb Classical Library edition, 1963.
Suint is in origin a French word, related to our sweat. The Latin word for suint is oesypum.