Origin: Gunpowder weapons first appeared in Western Europe in the 1320's, and the first English text to use the term gun is dated 1339. However, words like gunne, gonne, et al goes back further, describing mechanical siege engines. According to Bert S. Hall, this stems from the practise of naming such engines with the Old Norse female name Gunhilda (gunn-r means war and hild-r means battle). Later the word gun became intermixed or confused with the word gin (from engine) and was used as a generic term meaning any sort of siege engine.
Source: Bert S. Hall, Weapons & Warfare in Renaissance Europe, Baltimore 1997