petrous

As adjectives the difference between squamous and petrous

is that squamous is covered with, made of, or resembling scales; scaly while petrous is resembling rock or stone in its hardness.

As an adjective petrous

is resembling rock or stone in its hardness.

As a noun petrol is

(chiefly|au|nz|uk) petroleum, a fluid consisting of a mixture of refined petroleum hydrocarbons, primarily consisting of octane, commonly used as a motor fuel.

As adjectives the difference between petrous and petrosal

is that petrous is resembling rock or stone in its hardness while petrosal is (anatomy) of, pertaining to, or located near the petrous part of the temporal bone.

As a noun petrosal is

(anatomy) a petrosal bone.