collarbone
n.the long, thin bone that runs across the top of your chest, just below your neck. It connects your shoulder to your body.
n.the S-shaped bone that connects the shoulder to the sternum, forming the front part of the ribcage. It is a common site for fractures in sports or falls.
“She wore a low-cut shirt to show off her collarbone.”
“The athlete suffered a minor fracture to his collarbone after a collision during the final race.”
“In many mammals, the collarbone is vestigial or entirely absent, allowing for greater range of motion in the forelimbs, whereas in humans it provides structural support for the shoulder girdle.”
“For a deeper voice, men are encouraged to perform exercises known as neck crunches to strengthen their sternocleidomastoids —the long neck muscles running from the ear to the collarbone.”
From Middle English colar bane; equivalent to collar + bone.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.