Derived from Jackin (earlier Jankin), a medieval pet form of JOHN. American writers Jack London and Jack Kerouac were two famous bearers of this name.
Usage: English, Biblical
English form of Johannes, which was the Latin form of the Greek name Ioannes, itself derived from the Hebrew name Yochanan meaning "YAHWEH is gracious". This name owes its consistent popularity to two New Testament characters, both highly revered as saints. The first was John the Baptist, the forerunner of Jesus Christ and a victim of beheading by Herod Antipas. The second was the apostle John, also supposedly the author of the fourth Gospel and Revelation. The name has been borne by 23 popes, as well as kings of England, Hungary, Poland, Portugal and France. It was also borne by the poet John Milton and the philosopher John Locke.
My first name is in fact John. Everybody has always called me Jack (or Jackie) except in high school and college, when I inexplicably went as John.