Aneurysm - An abnormal widening or ballooning of a section of a blood vessel.  Aneurysms can rupture, leading to stroke.

Basilar Artery - The artery that supplies blood to the cerebellum, the brainstem, and the back of the brain.

Brainstem - The brain structure that is the major communication route among the brain, spinal cord, and peripheral nerves; controls heart rate, breathing, and other vital functions.

Cerebral Infarction - The death of part of the brain from a lack of oxygen-carrying blood.

Dysarthria - a language disorder characterized by difficulty with speaking or forming words.

Dysphagia - trouble eating and swallowing.

Embolism - A blockage of blood flow through a vessel in the brain by a blood clot that formed elsewhere in the body and traveled to the brain.

Emotional Lability - the term used when someone is more emotional and/or has difficulty controlling their emotions. It can happen with many neurological conditions and often happens after a stroke. Some people describe feeling as though all their emotions are “much nearer the surface” or more exaggerated after their stroke. For example some people may become upset more easily, or cry at things they would not have cried at before their stroke. Their emotional response is in line with their feelings, but is much stronger than before the stroke. For other people the symptoms can be more exaggerated, and some people find that they cry for little or no reason. Less commonly, people laugh rather than cry, but again the emotion is out of place and does not match how they are feeling at the time.

Hemiparesis - weakness on one side of the body. 

Hemiplegia - Paralysis of one side of the body.

Hemorrhage - Bleeding in the brain (intracerebral hemmorage) caused by the rupture of an intracranial (within the head) blood vessel.

Infarct - An area of tissue death due to a local lack of oxygen.

Ischemic - An ischemic stroke is death of an area of brain tissue (cerebral infarction) resulting from an inadequate supply of blood and oxygen to the brain due to blockage of an artery.

Paresis (paretic) - Incomplete paralysis or weakness of the limbs. 

Plegia - Lack of voluntary movement. 

Pons - A specific section of the brain formed by the rounded prominence on the front surface of the brainstem.

Subarachnoid hemorrhage - A cause of some strokes in which arteries on the surface of the brain begin bleeding.

Tissue plasminogen activator (abbreviated tPA) - is a protein involved in the breakdown of blood clots.  Because it works on the clotting system, tPA is used in clinical medicine to treat only embolic or thrombotic stroke.

Thrombosis - A blockage of blood flow through a vessel in the brain by a blood clot that formed in the brain itself.

Vertebral Artery - One of two blood vessels that run up the back of the neck and join at the base of the skull to form the basilar artery.