Oak or other bark containing tannic acid, used in making leather, and, when the acid is exhausted, used as a soft surface on race tracks.

橡树皮；其他含有鞣酸之树皮。

This material, after the tannin has been exhausted, spread to make a soft surface, as in a circus ring.

用以铺作柔软表面的单宁酸已耗尽的橡树皮(如铺于马戏场者)。