Kathleen was the fourth Kennedy child after Joe Jr., Jack, and Rosemary. Her middle name was Agnes, after her mother’s younger sister. Nobody but Mrs. Kennedy, however, called Kathleen anything but Kick, although everybody had forgotten where the nickname came from. It could have started as a mispronunciation of “Kathleen” and then turned to “Kick” to differentiate her from Kico, or Kathryn Convoy, the Kennedys’ Irish nurse. However Kathleen got her nickname, it seemed to suit her spunky, vivacious personality. She was brighter and quicker than any of the other children except her brother Jack. Jack had a keenly inquiring mind (he read everything he could get his hands on), but Kathleen was a better all-around student because she applied herself to her studies and never needed tutoring, as the other girls did. She favored Jack with her reddish-brown hair and blue-gray eyes, and was small and dainty, like her mother. Friends of the Kennedy’s thought that the boys rather than the girls were blessed with the refined good looks of the family. But Kick was so ebullient and sharp that no one ever thought of her as anything other than very pretty.
– Kathleen Kennedy: Her Life and Times