A salve was an ointment used to soothe areas of the body's surface.
Phlox used the epidermal layers of the Lyssarian Desert Larvae as a salve. The epidermis secreted a viral suppressant useful for treating cuts and bruises. (ENT: "Similitude")
In 2372, Julian Bashir created a salve for a dying Ekoria. She did not like its smell. (DS9: "The Quickening")
In 2373, Miles O'Brien asked Bashir if he had a salve for a rash on the back of Kira Nerys' thighs. (DS9: "Looking for par'Mach in All the Wrong Places")