Jo Definition
jō
joes
noun
A sweetheart.
Webster's New World
pronoun
A diminutive of the female given names Josephine, Joan or Joanna. Often used in conjoined names such as Jo Ann or Mary Jo.
Wiktionary
(biblical) Abbreviation of John.
Wiktionary
Origin of Jo
Alteration of joy
From American Heritage Dictionary of the English Language, 5th Edition