thoracic outlet syndromenoun [ U ]
uk/θəˌræs.ɪk ˈaʊt.lət ˌsɪn.drəʊm/us/θəˌræs.ɪk ˈaʊt.lət ˌsɪn.droʊm/abbreviation TOS specializeda group of disorders affecting the shoulders, neck, arms, and hands that can cause pain, loss of feeling, or the feeling of a lot of sharp points being put quickly and lightly into the body:
Thoracic outlet syndrome can be caused by compression of nerves or blood vessels in the area between the neck and shoulders.