Etymology

First attested 1654, from sub rosā, "under the rose", from sub, ("under") + rosā (meaning "rose"). The rose's connotation for secrecy dates back to Greek mythology. Aphrodite gave a rose to her son Eros, the god of love; he, in turn, gave it to Harpocrates, the god of silence, to ensure that his mother's indiscretions (or those of the gods in general, in other accounts) were kept under wraps. In the Middle Ages a rose suspended from the ceiling of a council chamber pledged all present - those under the rose, that is - to secrecy.

Adverb

sub rosa

1. In secret or covertly; privately or confidentially

   they held the meeting sub rosa

Noun

sub rosa

1. Slang. Used in Workers' Compensation cases to mean covert surveillance video used to catch Workers' Compensation applicants and show that they are in fact not injured. Also spelled subrosa.