Jankin (English): Nickname for John (God is gracious). It eventually turned into Jackin, and ultimately became the familiar Jack.
Jaunti (Basque): “Mister, lord.”
Jawar (Moorish Arabic)
Joceran (French): From Ancient Germanic roots Gaut (Goth) and hramn (raven). It may also have been influenced by Latin word gaudium (joy, delight).
Josquin (Dutch, French): Gallicized form of Josken, which can either be a nickname for Joseph (he will add) or Jodocus (lord). This name was borne by venerable French composer Josquin des Prez (ca. 1450/55–27 August 1521).
Jurian (Low German): Form of George (farmer), derived from Greek name Georgios and root georgos (farmer, earthworker). The specific roots of georgos are ge (earth) and ergon (work).
Jaida (Arabic): “Virtuous, good.”
Jawhara (Judeo–Arabic, Moorish Arabic): “Gem, jewel.”
Jerinne (Flemish): Possibly an elaborated form of Frisian name Jera (a nickname for Gertruda) or a feminine form of Jeremiah (God has uplifted).
Jocea (English): Feminine form of Joceus (lord).
Jocosa (English): Form of Joyce (lord). The spelling was inspired by the Latin word iocosus or jocosus (merry, playful).
Joia (English, French): “Joy,” from Old French joie, Late Latin gaudia, and Classical Latin gaudium. In the Jewish community, this was sometimes used as a secular form of Simcha (joy).
Judur (Moorish Arabic)
Junipera (Italian): “Juniper.”