The Collaborative International Dictionary of English v.0.48:

Venous \Ven"ous\, a. [L. venosus, from vena a vein. See Vein.]
   1. (Anat.) Of or pertaining to a vein or veins; as, the
      venous circulation of the blood.
      [1913 Webster]

   2. Contained in the veins, or having the same qualities as if
      contained in the veins, that is, having a dark bluish
      color and containing an insufficient amount of oxygen so
      as no longer to be fit for oxygenating the tissues; --
      said of the blood, and opposed to arterial.
      [1913 Webster]

   3. Marked with veins; veined; as, a venous leaf.
      [1913 Webster]

   Venous leaf (Bot.), a leaf having vessels branching, or
      variously divided, over its surface.

   Venous hum (Med.), a humming sound, or bruit, heard during
      auscultation of the veins of the neck in anaemia.

   Venous pulse (Physiol.), the pulse, or rhythmic
      contraction, sometimes seen in a vein, as in the neck,
      when there is an obstruction to the passage of blood from
      the auricles to the ventricles, or when there is an
      abnormal rigidity in the walls of the greater vessels.
      There is normally no pulse in a vein.
      [1913 Webster]

WordNet (r) 3.0 (2006):

venous
    adj 1: of or contained in or performing the function of the
           veins; "venous inflammation"; "venous blood as contrasted
           with arterial blood"; "venous circulation"