/ smɒk; NAmE smɑːk/ noun
1.
a loose comfortable piece of clothing like a long shirt, worn especially by women
2.
a long loose piece of clothing worn over other clothes to protect them from dirt, etc. :
an artist's smock
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WORD ORIGIN
Old English smoc woman's loose-fitting undergarment ; probably related to Old English smūgan to creep and Old Norse smjúga put on a garment, creep into.