Green’s Dictionary of Slang

(US) a person, used in direct address.

1920		F.S. Fitzgerald This Side of Paradise in Bodley Head Scott Fitzgerald III (1960) 199: ‘Going out?’ [...] ‘Uh-huh.’ ‘Where?’ ‘Couldn’t say, old keed.’.
1941		B. Schulberg What Makes Sammy Run? (1992) 40: He gave me that glad-hand business. ‘Okay, Alsie-palsie. Glad you’re gonna be with us, keed.’.
1953		W. Brown Run, Chico, Run (1959) 15: Come on, Chico. Come on, keed. Get in and make it snappy.
1965		J. Thompson Texas by the Tail (1994) 148: Some fun, hey, keed?
1978		R.D. Pharr Giveadamn Brown (1997) 183: ‘I don’t want hom to have any army at his side. Dig that real cool, keed’.