A pullover shirt is a type of shirt that does not require buttons or zippers to be put on. It is usually made of a lightweight material and is designed to be comfortable and easy to wear. The term 'pullover shirt' can also refer to a POLO shirt, which is a type of shirt with a collar, short sleeves, and a placket with two or three buttons at the neckline. POLO shirts are often made of cotton or a cotton blend and are popular for casual and semi-formal occasions.