"bing"...an interesting name for a search engine.

Bing, from Microsoft's perspective, the biggest competitor to Google till date. So what does "bing" mean. The first thing that came into my mind was "Chandler Bing", I am sure there are some ardent "Friends" fans in Microsoft but I doubt they would name their best effort yet engine with their favorite TV character. So, the curious mind I am, I went to google definitions and typed in "bing". Here are some results I got:

Bing is a Unix program which is essentially a ping with added network throughput measurements

A slag heap (also called bing, Boney piles, culm, waste coal, Terekons (Russian), gob piles, or slate dumps) is a pile built of accumulated tailings, which are by-products of mining

Bing is a Chinese term used to describe dough-based Chinese flatbreads, pancakes, unleavened dough foods, or indeed any food item with a flat disk

I wonder which one of these definitions made Microsoft pick "bing" as their search term, could it be the slag heap, I wonder.