Pronunciation: (shûrt'slēv"),[key] —adj. 1. not wearing a jacket; informally dressed: a shirt-sleeve mob. 2. warm enough to live or work in without wearing a jacket or coat: shirt-sleeve weather in November. 3. simple, plain, and informal; direct and straightforward in approach, manner, etc.: shirt-sleeve diplomacy.Also,shirt'sleeve",shirt'-sleeved",shirt'-sleeves".