The term 'collar style' can refer to two different crossword solutions: ETON and PETERPAN. ETON is a four-letter word that refers to a style of shirt collar characterized by a wide, stiff, buttoned band around the neck. This style was popularized by the English clothing brand Eton College in the 19th century. PETERPAN is an eight-letter word that refers to a style of shirt collar characterized by a rounded, curved shape. This style was popularized by the character Peter Pan in the early 20th century.