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.
That would be an aneurism I think
aneurysm
Dilation (orig. latin Dilatation), meaning 'widening' , 'extending' or change in volume. Example: Dilation of the ventricles of the heart, Vessel dilation, Dilation of the smooth muscles etc. Mydriatic is the medical term that pertains to dilating the pupils, such as the drops that you get at the eye doctor's office. Aneurysmal refers to dilation of an artery.
The medical term for dilation of a lymph vessel is lymphangiectasia. This condition can result in the abnormal dilation or widening of lymphatic vessels. It can occur due to various factors such as inflammation, infection, or tumors.
Lymphangiectasis is abnormal dilation of the lymph vessels.
A hemangioma is the medical term meaning tumor of blood vessels.
This is called vasodilation. Vaso meaning vessel and dilation meaning getting wider.
Narrowing of the blood vessels is called atherosclerosis.
vascular
Fluorescein angiography is the medical term meaning radiographic study of the blood vessels of the retina. This process can examine retinal vessels in the case of diabetes.
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.
Avascular is the medical term meaning without blood vessels.
Blood vessels
Vasculitis