Antidiuretic hormone, also called arginine vasopressin (AVP), is a hormone produced by the hypothalamus in the brain and stored in the posterior pituitary gland at the base of the brain. ADH helps regulate water balance in the body.
Stew meat is typically cut into 3/4 inch to 1 1/2 inch cubes and cooked with vegetables, such as potatoes, carrots, celery and onions cut into similar sizes. You can purchase the meat precut and packaged for convenience or buy a roast and cut it yourself. Precut stew beef is usually more expensive per pound than roasts.
You've probably had tough beef stew meat. That is meat which hasn't been cooked long enough. Stew meat should be cooked for hours and hours in liquid (such as beef or veal stock) so the liquid has time to penetrate the meat and make it tender. Otherwise you end up with a piece of beef as tough as a shoe sole and about as flavorful.