Purbach is named after the 15th century Austrian astronomer Georg von Peuerbach. Like many of the craters on the Moon's near side, it was named (in the Latin form, 'Purbachius') by Giovanni Riccioli, whose 1651 nomenclature system has become standardized. Earlier lunar cartographers had given the feature different names: Michael van Langren's 1645 map calls it Christierni IV Reg. Daniae, after King Christian IV of Denmark, and Johannes Hevelius grouped it with Walther and Regiomontanus under the name Mons Libanus, after Mount Lebanon.