The Etymology and idioms of "Delhi" is uncertain, but many possibilities exist. The very common view is that its eponym is Dhillu or Dilu, a king of the Mauryan dynasty, who built the city in 50 BC and named it after himself. The Hindi/Prakrit word dhili ("loose") was used by the Tomaras to refer to the city because the Iron Pillar built by Raja Dhava had a weak foundation and was replaced. The coins in circulation in the region under the Tomaras were called dehliwal. Some other historians believe that the name is derived from Dilli, a corruption of dehleez or dehali—Urdu for 'threshold'—and symbolic of city as a gateway to the Gangetic Plain. Another theory suggests that the city's original name was Dhillika.
Delhi is referenced in various idioms of North Indian and Pakistani languages. Examples include -
- Abhi Dilli door hai (or, its Persian version, Hanooz Dilli door ast) literally meaning Delhi is still far away, which is generically said about a task or journey is still far from complete.
- Dilli dilwalon ka shehr or Dilli Dilwalon ki meaning Delhi belongs to the large-hearted/daring.
- Aas-paas barse, Dilli pari tarse literally meaning it pours all around, while Delhi lies parched. An allusion to the sometimes semi-arid climate of Delhi, it idiomatically refers to situations of deprivation when there is plenty all around.