Definitions for old boyˈoʊld ˈbɔɪ for 1 ; ˈoʊld ˌbɔɪ for 3
Random House Webster's College Dictionary
old boyˈoʊld ˈbɔɪ for 1 ; ˈoʊld ˌbɔɪ for 3(n.)
an adult male, esp. in the South.
Category: Common Vocabulary, Informal
Ref: Compare good old boy.
Chiefly Brit. an alumnus, esp. of a boys' preparatory or public school.
Origin of old boy:
old boy, old man(noun)
a familiar term of address for a man
a vivacious elderly man
a former male pupil of a school
An alumnus, especially of a public school.
Affectionate term of address for a man.
A former member of a group