Jake (rescue dog) definition

Originally a medieval variant of Jack, derived from John; today also used as a diminutive form of Jacob and James.

1927 Ernest Hemingway, The Sun Also Rises, Chapter III:

Brett smiled at him. "I've promised to dance this with Jacob," she laughed. "You've a hell of a biblical name, Jake."
1985 Ed McBain: Snow White and Rose Red: page 10:

Her attendant - Jake, she had called him, which seemed an appropriate name for a redheaded, no-neck redneck with the muscles of a dedicated weight lifter - - -