Oxford bags are a type of very baggy trousers, traditionally worn by students at Oxford University; they were particularly popular during the period 1920-1950.
At various points during the 20th and 21st Centuries, Oxford bag-style trousers have been a women's fashion item.
A boater is a type of summer hat, usually made of straw. It was a popular form of headgear for men during the late 19th and early 20th Century; slightly different styles of boater were also worn by women.
Later on, it became part of some summer school uniforms, and remains so in certain English boys' public schools, and at boys' schools in Australia, New Zealand and South Africa.
Follow this link to see modern Oxford bags for women;
this link to see old-fashioned Oxford bags for men;
this link to see old-fashioned Oxford bags gone mad!