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
an agent (such as a sympathetic nerve fiber or a drug) that induces or initiates constriction of blood vessels
a substance that constricts or narrows the blood vessels; vasopressin and angiotensin are vasoconstrictors
Causing constriction of the blood vessels; as, the vasoconstrictor nerves, stimulation of which causes constriction of the blood vessels to which they go