on the DL
In a state of secrecy or minimal public knowledge; being known only by a select few people. ("DL" is an initialism for "down low.") Keep this on the DL, but Janet is planning to break up with Kevin next week. My parents know about the pregnancy, but I'd like it to stay on the DL otherwise.
on the DL
mod. as a secret; secretly; on the QT. (From down low.) She’ll get in trouble because they did it on the DL.