Sampi or Disigma is a mysterious Greek symbol. Its meaning is still debated today. Some believe it to be a replacement of 'san'. Before that, it was a letter that was used in the Greek alphabet in a few Greek cities in the 5th century BC. At that time, it looked like or . It was probably pronounced like "ts" or "tch" in the dialect of those cities. Over time, it was changed from to or and at last to . Eventually, the letter came out of use, while it was still used to denote "900" in the system of Greek numerals.