The Kyrgyz (also spelled Kirgiz, Kirghiz) are a Turkic people living primarily in Kyrgyzstan. There are several etymological theories on the ethnonym "Kyrgyz." The word "Kyrgyz" is derived from the Turkic word "forty", with -Iz being an old plural suffix, referring to a collection of forty tribes. Kyrgyz also means "imperishable", "inextinguishable", "immortal", "unconquerable" or "undefeatable", presumably referring to the epic hero Manas who, as legend has it, unified undefeated forty tribes against the Khitans. This version has an obvious popular appreciation. Historical evidence for many conflicts with other peoples also supports this theory. The Chinese transcription "Tse-gu" (Gekun, Jiankun) allows to restore the pronunciation of the ethnonym as Kirkut (Kirgut) and Kirkur (Kirgur). Both forms go back to the earliest variation Kirkun (Chinese Tszyan-kun) of the term "Kyrgyz" meaning "Field People", "Field Huns".
Contributions by Scythian1, Barefact, and Khoikhoi.