What is the root/origin of Delhi/Dilli name?

Referring to India's capital. On wiki and newspaper article, I could gather multiple stories, however, none with actual proof. 1. King Dhillu or Dilu in 50 BCE

2. Dhili/Dhila (Loose in Prakrit and hindustani) pillar

3. Dil meaning eminence!!

History is proper from 1000 CE onwards of Tomar rule. However, before that everything is just hearsay. Mahabharat connection is most BS theory as none archeological evidence even suggest that! There is mention of Ashoka pillar in the area, but no mention of city name.

I am looking for this word's roots, origin from before of 1000 CE. Any mention in inscription, literature witty references will be helpful.

Also, there is no clarity on when the city was established. Exact time period and ruling clan, language influence will also help!

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