(Science: pharmacology) A semisolid unctuous substance, neutral, and without taste or odour, derived from petroleum by distilling off the lighter portions and purifying the residue. It is a yellowish, fatlike mass, transparent in thin layers, and somewhat fluorescent. It is used as a bland protective dressing, and as a substitute for fatty materials in ointments.
petrolatum is the official name for the purified product. Cosmoline and vaseline are commercial names for substances essentially the same, but differing slightly in appearance and consistency or fusibility.