An Oxford shirt is defined by the unique weave of its fabric as well as the history of the shirt itself.
In a variation of the plain weave used in chambray, the oxford shirt uses a basketweave, bundling two threads together and woven as one in the warp (vertical) and a heavier yarn in the weft (horizontal)—or vice versa—and often in a different color to give it a distinctive pattern. This weave gives the fabric a recognizably “Oxford” look and texture.
The Oxford shirt was originally made by Scottish fabric mills in the 19th century and is actually one of four shirt fabrics named after universities. The others were Harvard, Yale, and Cambridge; but only the Oxford remains.
Another distinctive feature is the button-down collar. Because the fabric was comfortable and breathable, Polo players would wear long sleeve Oxford shirts during their matches -- as would the spectators. To keep the wind from blowing their collars up, players and spectators alike would button their collars down to the shirt. The modern-day Oxford shirt still usually (but not always) features the button-down collar.