On the QT is an idiom that means to do something secretly or in a confidential manner. There are many synonyms for this phrase, including behind closed doors, hush-hush, under the radar, confidentially, privately, in a covert manner, and sneaky. These words can be used interchangeably with on the QT to convey the same meaning of keeping something hidden or secret. Other synonyms for on the QT can include in secret, on the sly, on the down-low, behind the scenes, unbeknownst to others, and clandestinely. These synonyms can be useful for expressing secrecy or confidentiality in a variety of settings, including business, relationships, politics, and personal matters.