Quad as a word or prefix usually means 4. It may refer to:

• Quadrilateral Security Dialogue, a strategic security dialogue between Australia, India, Japan, and the United States
• Quadrilateral group, an informal group that includes the trade spokesmen of the United States, Japan, Canada, and the European Union
• I2U2 Group, a strategic partnership between the United States, India, Israel, and United Arab Emirates; also known as the "Middle East Quad"
• Quad Cities, a group of five cities straddling the boundary between the U.S. states of Iowa and Illinois
• The "Quad", the senior members of the Cameron–Clegg coalition government in the United Kingdom from 2010 to 2015

• Matthias Quad (1557–1613), engraver and cartographer working in Germany
• Quad (film), 2020
• Quad (music), a musical project by Gary Ramon
• Quad (play), by Samuel Beckett
• The Quad (TV series), 2017
• Quad (arts centre), in Derby, United Kingdom
• Quad Cinema, art house in New York City, New York
• Quad (studio), a Japanese animation studio

• Quad (company), an American marketing solutions company
• Quad Electroacoustics, a British manufacturer of audio equipment

• Quadriplegic, a person paralyzed in all four limbs
• Quadriceps, a large leg muscle group
• Quadruplets, four children from a multiple birth

• Quad (figure skating), a figure skating jump with four revolutions
• Quad scull, a boat configuration of four rowers
• Quad skates, roller skates with two wheels on each of two axles
• Quad, one of the divisions in wheelchair tennis
• Quadruple-double, a statistical accomplishment in basketball
• Quadrennium, the 4-year training cycle between Olympic games

• Quad bike or all-terrain vehicle, a light off-road vehicle
• Quad, a tandem bicycle with four seats
• Quadracycle, a four-wheeled human-powered land vehicle
• Jeffery Quad, a four-wheel drive truck
• Quadcopter, a four-rotor helicopter
• Quad, a chairlift in skiing which carries four persons
• Quad, or railroad speeder, a motorized vehicle used for maintenance on railroads
• Quad (rocket), an autonomous rocket by Armadillo Aerospace

• QUAD (cipher), a stream cipher
• QUaD, a microwave telescope at the South Pole
• Quad antenna, a directional antenna
• Quadraphonic sound, four-channel sound
• Quadruplex videotape, video tape format
• Quad flat package, a type of package for surface mounted integrated circuits
• Star quad cable, four insulated conductors twisted together

• Quad (unit), unit of energy, short for quadrillion, 10¹⁵ BTU
• Quad (geography), a United States Geological Survey topographical map
• Quad (typography), a spacer used in letterpress type
• Quad poster, a common UK size of film poster
• Quadrangle (architecture), a space or courtyard bordered by buildings
• Quadrat, in ecology, a small study area or a frame used to define it
• Quadrilateral, in geometry
• Quadrupel, a Belgian beer
• Quadruple combination, the four books that comprise the canon of the LDS church
• The Quad Casino (now The Linq), on the Las Vegas Strip
• Four-of-a-kind in poker
• Sako Quad, a Finnish bolt-action rifle
• Morris C8, a WWII era artillery tractor

• Quadrangle (disambiguation)
• All pages with titles containing Quad