By stealth adverb
Used when you move or act quietly and carefully so as not to be seen or heard, especially in an undetected way; silently and secretly.
Company policy had been changed by stealth without consultation; therefore, the meeting was immediately held yesterday.
The thieves broke into my house by stealth. We lost a lot of valuables.
A thing is known about by only a few people and kept hidden from others because it makes somebody feel ashamed.
Very quiet
To be secretly working together
A person who contributes important work to the organization but is kept secret.
To secretly punish or rebuke someone for doing something.
The origin of this expression is not clear.