1. (in vertebrates) a bony or cartilaginous arch supporting the forelimbs.
2. Also called shoulder girdle. (in humans) the bony arch formed by the clavicles, or collarbones, and scapulas, or shoulder blades. Also called pec'toral arch'.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.