Buckskin was a type of leather made from deer that was used as a clothing material. It was noted for being worn by people in the Old West.
In 2375, when invited by Julian Bashir and Miles O'Brien to join in their holoprogram of the Battle of the Alamo, Vic Fontaine declined, saying that he didn't look good in buckskin. (DS9: "Badda-Bing, Badda-Bang")