whale's tail

plural whale's tails

1. slangThe distal bifurcation of the left anterior descending coronary artery.

   It then bifurcates distally and tapers out as a "whale's tail" at the cardiac apex, although sometimes it wraps around the apex to supply part of the inferior wall.

   2007, Eric J. Topol, Robert M. Califf, Textbook of Cardiovascular Medicine, Lippincott Williams & Wilkins, →ISBN, page 1227

   1 more example

   […] anterior descending coronary artery (i.e. the "mustache," "pitchfork," or "whale's tail"; Fig. 18.6, top); in the circumflex system, the distal bifurcation of the segment with the longest total distance that includes the[…]

   2000, Donald S. Baim, William Grossman, Grossman's Cardiac Catheterization, Angiography, and Intervention, Lippincott Raven

2. Used other than figuratively or idiomatically: The tail of a whale.
3. slangAn alternative expression of the whale tail phenomenon where a thong peeks out above the waistband.

   Another distraction occurs when pants ride low in the back and expose thong underwear, a phenomenon students have dubbed whales' tails...

   2004, Tom Quinn, “Updated Dress Code Addresses New Styles”, in The Oregonian