The Collaborative International Dictionary of English v.0.48:

Coronary \Cor"o*na*ry\, n.
   1. A small bone in the foot of a horse.
      [Webster 1913 Suppl.]

   2. Informal shortening of coronary thrombosis, also used
      informally to mean heart attack.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Coronary \Cor"o*na*ry\ (k?r"?-n?-r?), a. [L. coronarius: cf. F.
   coronaire.]
   1. Of or pertaining to a crown; forming, or adapted to form,
      a crown or garland. "Coronary thorns." --Bp. Pearson.
      [1913 Webster]

            The catalogue of coronary plants is not large in
            Theophrastus.                         --Sir T.
                                                  Browne.
      [1913 Webster]

   2. (Anat.) Resembling, or situated like, a crown or circlet;
      as, the coronary arteries and veins of the heart.
      [1913 Webster]

WordNet (r) 3.0 (2006):

coronary
    adj 1: surrounding like a crown (especially of the blood vessels
           surrounding the heart); "coronary arteries"
    n 1: obstruction of blood flow in a coronary artery by a blood
         clot (thrombus) [syn: coronary thrombosis, coronary]