birthmark
Synonym discussion
Sense: noun/1
Birthmark is the best word when the skin mark has been there since birth. Mole often means a small dark spot, but a mole may appear later in life, so it is not always a birthmark. Mark is much broader and can describe many kinds of signs on the skin, including dirt, ink, or an injury. Scar is different again, because it comes after a cut, burn, or operation. So you can say Lior has a birthmark above her eye, but not a scar unless the skin changed after damage. If a doctor asks about a mole, the question may be about skin health, not only about a mark from birth.
Etymology
Birthmark is a native English compound made from birth and mark. English speakers built the word in a direct way to mean a mark a person has from birth, rather than borrowing a longer medical term from another language.