Meridian or a meridian line (from Latin meridies via Old French meridiane, meaning “midday”) may refer to

• Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon
  • Central meridian (astronomy)
• Meridian (geography), a longitude line, i.e. a line of constant longitude, or in other words an imaginary arc on the Earth's surface from the North Pole to the South Pole
  • Meridian arc, the distance between two points with the same longitude
  • Prime meridian, origin of longitudes
  • Principal meridian, arbitrary meridians used as references in land surveying
• Meridian line, used with a gnomon to measure solar elevation and time of year
• Autonomous sensory meridian response, a static-like or tingling sensation on the skin
• Meridian (vision), polar coordinate system for the visual field

• Meridian, California (disambiguation), U.S., multiple California towns named Meridian
• Meridian, Colorado, U.S.
• Meridian Village, Colorado, U.S.
• Meridian, Florida, U.S.
• Meridian, Georgia, U.S.
• Meridian, Idaho, U.S.
• Meridian, Mississippi, U.S.
• Meridian, Nebraska, U.S.
• Meridian, New York, U.S.
• Meridian, Oklahoma (disambiguation), U.S., multiple Oklahoma towns named Meridian
• Meridian, Pennsylvania, U.S.
• Meridian, Seattle, Washington, U.S.
• Meridian, Texas, U.S.

• Meridian Township, Clinton County, Illinois, U.S.
• Meridian Charter Township, Michigan, U.S.

• Meridian (Amtrak station), or Union Station, Meridian, Mississippi, U.S.
• Meridian Mall, Meridian Township, Michigan, U.S.
• Meridian Mall, Dunedin, New Zealand
• Meridian Hall (Washington, D.C.), listed on the National Register of Historic Places in Washington, D.C., U.S.
• Meridian Manor, listed on the National Register of Historic Places in Washington, D.C., U.S.
• Meridian Mansions, listed on the National Register of Historic Places in Washington, D.C., U.S.

• Lake Meridian, Kent, Washington, U.S.
• Meridian Creek, a stream in Alaska, U.S.
• Meridian Glacier, Graham Land, Antarctica
• Meridian Peak, Eagles Nest Wilderness, near Vail, Colorado, U.S.
• Meridian Plantation, a quail-hunting plantation in Leon County, Florida, U.S., established in 1915

• Meridian, a fictional country in the animated web series MechWest

• Meridian (novel), 1976 novel by Alice Walker
• Meridian (comics), 2000–2004 comic book series published by CrossGen
• Meridian (W.I.T.C.H.), a fictional realm in the Italian comic book series W.I.T.C.H.
• Meridians: Feminism, Race, Transnationalism (est. 2000), an interdisciplinary peer-reviewed feminist journal

• Meridian: Kiss of the Beast, 1990 horror and romance film directed by Charles Band
• "Meridian" (Star Trek: Deep Space Nine), 1994 episode of the series
• "Meridian" (Stargate SG-1), 2002 episode of the series
• Meridian (film), 2016 film noir thriller directed by Curtis Clark
• ITV Meridian (formerly Meridian Broadcasting), ITV station for the south and south-east of England

• Meridian Records, record label
• Meridian Dawn, modern death metal band
• Meridian Green, California-based folk musician
• Meridian, 1997 album by Ian Pooley
• Meridian (Miriam Yeung album), 2007 album by Miriam Young
• Meridian (album), 2012 album by Pinegrove
• "Meridian", 2017 song by Odesza from A Moment Apart

• Meridian (Hepworth), 1960 bronze sculpture by British artist Barbara Hepworth

• Meridian Audio, British manufacturer of audio equipment
• Meridian Credit Union, credit union based in Ontario, Canada
• Meridian Energy, New Zealand electricity generation and electricity retailing company
• Nortel Meridian, popular PBX telephone system
• Meridian, a health insurance company owned by Centene Corporation

• Meridian High School (disambiguation)
• Meridian Technology Center, Stillwater, Oklahoma, United States

• Meridian (train), British Rail Class 222 trains
• Meridian (commuter rail), former commuter rail service in Germany operated by the Bayerische Oberlandbahn
• MS Meridian, cruise ship constructed in 1961
• Meridian (shipwreck), sunken schooner in Lake Michigan
• Piper Meridian, turboprop model of the Piper PA-46 aircraft
• Meridian LRT station, an LRT station on the Punggol LRT line East Loop in Singapore
• Meridian Airways, a defunct Ghanaian airline

• Bill Meridian (fl. 1972–1983), a financial astrologer
• Meridian (Chinese medicine), traditional Chinese medical theory, often employed in acupuncture
• Meridian (horse), American Thoroughbred racehorse, winner of 1911 Kentucky Derby
• Meridian (Nosgoth), the capital of Nosgoth in Blood Omen 2: Legacy of Kain
• Meridian (satellite), a series of Russian military communications satellites
• Meridian F.C., English non-league football club
• Meridian Hospital, a private hospital in Port Harcourt, Rivers State, Nigeria
• Meridian Lossless Packing, a lossless audio compression technique used in DVD-Audio, HD DVD, and many Blu-ray discs

• Meridian 59, online game
• Meridian Hill Park, a park in Washington D.C., U.S.
• One Meridian Plaza, an office building that burned down in 1991 in Philadelphia, Pennsylvania, U.S.