old boy

Short definition from Wiktionary

Noun

1. 1
   An alumnus, especially of a public school.
2. 2
   A former member of a group.
3. 3
   A man with an established network of friends who assist one another in social and business situations; a good old boy.
4. 4
   An elderly man.
5. 5
   A familiar term of address for a man of any age.