1
general::
Unofficially, in confidence, not for publication, as in What he was about to say, he told the reporters, was strictly off the record. Probably alluding to striking evidence from a court record (because it is irrelevant or improper), this term came into wide use in the mid-1900s, especially with reference to persons who did not wish to be quoted by journalists. For antonyms, see GO ON RECORD; JUST FOR THE RECORD.
American Heritage Idioms
2
general::
Phrase(s): off the record
Fig. unofficial; informal. (Of comments to the press that one does not want reported.) • This is off the record, but I disagree with the mayor on this matter. • Although her comments were off the record, the newspaper published them anyway.
McGrawhill's American Idioms And Phrasal Verbs