The veins and their tributaries are collectively called the venous system. The other part of the circulation is the arterial system.
Varicose veins, swollen tortuous veins, are called varices in medical terms.
Blood vessels
Venopathy; phlebopathy
varicocele
Varicose Veins.
The answer to that is varicose veins.
Hemorrhoids are dilated or varicose veins of the rectum or anus. They can be painful or painless.
Hemorrhoidectomy
A vascular surgeon specializes in the treatment of veins.
Sclerotherapy is a commonly used treatment of spider vein.
lipedema
The medical term for abnormal dilation of a vessel is "aneurysm." Aneurysms can occur in arteries or veins and are classified based on their location and cause. They can be asymptomatic or present with symptoms such as pain or rupture.