Definition & Meaning of "on the q.t."

What is the origin of the idiom "on the q.t." and when to use it?

The idiom "on the q.t." originated from the phrase "quiet as a cat," which was later shortened to "quiet as a QT." Over time, "QT" evolved to "q.t." and eventually became the idiom "on the q.t." It refers to keeping something secret, confidential, or discreetly hidden from others. The phrase implies a need for caution or secrecy, often suggesting that the information or activity being discussed should not be openly disclosed or shared.