A smock is a loose, protective garment worn over your regular clothes to keep them clean while you work. Think of the oversized shirts you might wear during art class to protect your outfit from paint splatters and glue: that's a smock. Artists wear smocks in their studios. Scientists wear white lab smocks (often called lab coats) to protect their clothes from chemicals. Historically, farmers and craftspeople wore smocks as everyday work clothes.

Today smock refers to any loose protective covering worn over clothes. A smock is typically made of cotton or another washable fabric and slips on easily over your head. Unlike an apron, which only covers your front, a smock covers your arms and most of your body like a baggy shirt or dress.

You'll also hear smocking, which refers to a decorative sewing technique that gathers fabric into a stretchy, honeycomb pattern, often seen on fancy clothing. But when someone tells you to “put on your smock,” they just mean the protective covering that keeps paint, clay, or cooking ingredients off your good clothes.