birthmark

birthmark
birth‧mark /ˈbɜːθmɑːk $ ˈbɜːrθmɑːrk/ noun [countable]
a permanent mark on your skin that you have had since you were born:
    Paul had a birthmark on his left cheek.
     

THESAURUS

■ a mark on your skin
   ▪ blemish a mark on your skin that spoils its appearance: John grew a beard to hide the blemishes on his chin.
   ▪ mole a small dark, sometimes raised, mark on your skin: Some moles may become cancerous. | Helena found a mole on her arm which had definitely not been there before.
   ▪ freckles small light brown marks on your skin, especially on your face but also on your arms, shoulders etc: She had a light sprinkling of freckles across her nose.
   ▪ birthmark a permanent mark on your skin that you have had since you were born: There was a small birthmark on her left cheek.
   ▪ bruise a purple or brown mark on your skin that you get because you have fallen or been hit: Her legs were covered in cuts and bruises.
   ▪ scar a permanent mark on your skin, caused by a cut or by something that burns you: The injury left a small scar on his forehead.
   ▪ pimple/zit (also spot British English) a small raised red mark or lump on your skin, which usually appears when a child is between 12 and 18 years old: When I was a teenager I had terrible spots. | The boy had a few pimples under his chin.
   ▪ wart a small hard raised mark on your skin caused by a virus: His face was covered in hairy warts.
   ▪ blister a small area of skin that is swollen and full of liquid because it has been rubbed or burned: There was a blister on his arm where the boiling milk had splashed him.
   ▪ rash an area of small red spots on your skin, caused by an illness or an allergy: I can’t eat strawberries - they give me a rash.