'Pressor' definitions:

Definition of 'pressor'

(from WordNet)
adjective
Increasing (or tending to increase) blood pressure; "pressor reflexes"
noun
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]

Definition of 'Pressor'

From: GCIDE
  • Pressor \Press"or\, a. (Physiol.) Causing, or giving rise to, pressure or to an increase of pressure; as, pressor nerve fibers, stimulation of which excites the vasomotor center, thus causing a stronger contraction of the arteries and consequently an increase of the arterial blood pressure; -- opposed to depressor. --Landois & Stirling. [1913 Webster]