vasoconstrictor n 1: any agent that causes a narrowing of an opening of a blood vessel: cold or stress or nicotine or epinephrine or norepinephrine or angiotensin or vasopressin or certain drugs; maintains or increases blood pressure [syn: {vasoconstrictor}, {vasoconstrictive}, {pressor}]
Vasoconstrictor \Vas`o*con*strict"or\, n. (Medicine, Physiology) A substance which causes constriction of the blood vessels. Such substances are used in medicine to raise abnormally low blood pressure. [PJC]
Vasoconstrictor \Vas`o*con*strict"or\, a. (Physiol.) Causing constriction of the blood vessels; as, the vasoconstrictor nerves, stimulation of which causes constriction of the blood vessels to which they go. These nerves are also called {vasohypertonic}. [1913 Webster]