The term 'shirt ornament' can be summarized as a small decorative item that is attached to a shirt. The crossword solution for this term is 'STUD', which is a type of shirt ornament that is typically made of metal and has a flat back with a sharp point on the front. It is usually secured to the shirt by pushing the point through the fabric and then flattening the back against the inside of the shirt. Studs are often used to add a decorative touch to a shirt, and they come in a variety of shapes and sizes.