Democritus is a lunar impact crater that is located on the northern part of the Moon, just to the north of the Mare Frigoris.

It forms not quite a circle, with outward notch-like bulges that give it a slightly irregular shape.

Like many of the craters on the Moon's near side, it was given its name by Giovanni Riccioli, whose 1651 nomenclature system has become standardized.

[1] Earlier lunar cartographers had given the feature different names: Michael van Langren's 1645 map calls it "Alfonsi IX Reg.

[3] By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Democritus.