Units and measurements

• Quart, a measure of volume in traditional systems of units
• Quarter, a unit of mass in Imperial units, equal to 2 stones or a quarter of a long hundredweight; one quarter = 12.70058636 kg
• QT interval, a measurement used in cardiology

Businesses and products

• QuikTrip, a convenience store chain
• "Quiet Trader", a trademark applied to the cargo version of the BAe 146 jet
• Quadra-Trac, a four-wheel-drive system developed by Jeep

Computing

• Qt (toolkit), a cross platform graphical widget toolkit for the development framework of GUI computer programs
• QuickTime, a multimedia technology from Apple Inc.

Miscellaneous

• QT: QueerTelevision, an LGBT newsmagazine which aired on Canada's CityTV in the 1990s
• Qiryat Tivon, a local council in the Haifa District of Israel
• Quantification theory, a formal system of logic, also known as predicate calculus
• Quentin Tarantino, an American film director
• "quiet", in the slang expression "on the Q.T." (pronounced as two letters) - see Wiktionary definition 2