Meaning of J in English
J is the tenth letter of the English alphabet. It is a later variant form of the Roman letter I, used to express a consonantal sound, that is, originally, the sound of English y in yet. The forms J and I have, until a recent time, been classed together, and they have been used interchangeably.
Webster's Revised Unabridged English Dictionary. Пересмотренный полный словарь английского языка Webster. 2012