Silly (French pronunciation: [sili] ⓘ; Dutch: Opzullik; Walloon: Chili) is a municipality of Wallonia located in the province of Hainaut, Belgium.

The total area is 67.68 square kilometres (26.13 sq mi) which gives a population density of 118 inhabitants per km2.

The name of the town derives from its stream, called the Sille (French) or Zulle (Dutch), and has no relation to the English word.

In the English-speaking world, it has frequently been noted on lists of unusual place names.

[2] The municipality consists of the following districts: Fouleng, Gondregnies, Graty, Hellebecq, Hoves, Silly, Thoricourt, and Bassilly.