Nevus is the medical term meaning birthmark; the plural form is nevi.
The most typical birthmark meeting that description is a strawberry hemangioma.
Birthmarks that contain blood vessels are called superficial hemangiomas. These vary from the "strawberry angiomas" to the capillary distention known as "port wine stains". Some hemiangiomas are caused by small skin tumors and some are simple lesions. These marks differ from "moles" (nevi) which are not primarily vascular.
Nevus flammeus is a birthmark due to dilation of small blood vessels. On the neck, the lay term for this birthmark is "stork bite." Elsewhere, it's often called a port-wine stain.
Anacusis is the medical term meaning complete deafness.
Syncope is the medical term meaning fainting.
Lamina is the medical term meaning layers.
Sensation is the medical term meaning feeling.
Eructation is the medical term meaning burping.eructation
Atrophy is the medical term meaning shrinking.
Metastasize is the medical term meaning "to spread."
Stasis is the medical term meaning stopping.
Strabismus is the medical term meaning cockeye.