PETROGRAPHY
Pe*trog"ra*phy, n. Etym: [Petro + -graphy.]
1. The art of writing on stone.
2. The scientific description of rocks; that department of science which investigates the constitution of rocks; petrology.
PETROHYOID
Pet`ro*hy"oid, a. Etym: [Petro + hyoid.] (Anat.)
Defn: Pertaining to petrous, oe periotic, portion of the skull and the hyoid arch; as, the petrohyoid muscles of the frog.
PETROL
Pe*trol", n.
Defn: Petroleum. [R.]
PETROLATUM
Pet`ro*la"tum, n. (Chem. & Pharm.)
Defn: A semisolid unctuous substance, neutral, and without taste or odor, 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. U. S. Pharm.
Note: 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.