Without special protection, in street clothes.(noun)
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Use "shirtsleeves" in a sentence
"I thought the Right was all about protocol, seeing as how upset many of them were that OUR President was in shirtsleeves in the Oval Office."
"But from Albuquerque to Richmond, Virginia, the overall scene is similar: President Obama, standing in shirtsleeves with a cordless microphone, talking to a small crowd of people."
"Ben is in shirtsleeves, Tiffany's in a checked skirt."