Definition from Wiktionary, the free dictionary
- (idiomatic) The closest of friends of a person.
1921, Edward W. Bok, The Americanization of Edward Bok:
- It was upon his return to London that Bok learned, through the confidence of a member of the British “inner circle,” the amazing news that the war was practically over: that Bulgaria had capitulated and was suing for peace; ...
closest of friends