It's a last name. It is also a diminutive of hard, which was an ancient coin. It is also called durillo to several species of plants, used to make seeds. I know they call the plant Amelanchier ovalis, which is from the Rosaceae family and has medicinal uses (curnia, corruñé, griñolera); also to the Viburnum tinus of the family Adoxaceae, which is also for medicinal uses ( Laurel of Alexandria, Sanguillo, orillera); cornus sanguinea, from the cornaceae family, also called cornejo, sanguiño or sanguino.