meaning of vasoconstrictor
1. 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.
2. A substance which causes constriction of the blood vessels. Such substances are used in medicine to raise blood pressure.
3. 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