The Collaborative International Dictionary of English v.0.48:

Jugular \Ju"gu*lar\, n. [Cf. F. jugulaire. See Jugular, a.]
   [1913 Webster]
   1. (Anat.) One of the large veins which return the blood from
      the head to the heart through two chief trunks, an
      external and an internal, on each side of the neck; --
      called also the jugular vein.
      [1913 Webster]

   2. (Zool.) Any fish which has the ventral fins situated
      forward of the pectoral fins, or beneath the throat; one
      of a division of fishes (Jugulares).
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Jugular \Ju"gu*lar\, a. [L. jugulum the collar bone, which joins
   together the shoulders and the breast, the throat, akin to
   jungere to yoke, to join: cf. F. jugulaire. See Join.]
   [1913 Webster]
   1. (Anat.)
      (a) Of or pertaining to the throat or neck; as, the
          jugular vein.
      (b) Of or pertaining to the jugular vein; as, the jugular
          foramen.
          [1913 Webster]

   2. (Zool.) Having the ventral fins beneath the throat; --
      said of certain fishes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

jugular
    adj 1: relating to or located in the region of the neck or
           throat; "jugular vein"
    n 1: veins in the neck that return blood from the head [syn:
         jugular vein, vena jugularis, jugular]
    2: a vital part that is vulnerable to attack; "he always goes
       for the jugular"