J (disambiguation)

J is the tenth letter of the Latin alphabet. It can also refer to the following.

Science, mathematics and computing

• In astronomy,
  • J stands for Jupiter, as in S/2003 J 18, the eighteenth natural satellite of Jupiter discovered in 2003.
  • J is a provisional designation prefix for any comet, asteroid, or minor planet discovered between May 1 and 15 of a year.
• In computing, J, J# and J++ are programming languages.
• In genetics,
  • Haplogroup J (mtDNA) is a human mitochondrial DNA (mtDNA) haplogroup.
  • Haplogroup J (Y-DNA) is a Y-chromosomal DNA (Y-DNA) haplogroup.
• In physics,
  • J is the symbol for the joule, the SI unit of energy.
  • j or J is the symbol for current density. For directional current densities ${\vec {j}}$ = (j_x, j_y, j_z) or j are used.
  • j is used for the imaginary unit (${\sqrt {-1}}$) in fields (such as electrical engineering) where i is traditionally used to denote electric current.
  • J is the symbol for polar moment of inertia.
• In mathematics,
  • j is the index variable commonly used after i.
  • j denotes the second imaginary unit of a quaternion.
  • J is used for Bessel functions.
  • j is used as the unit vector along the y axis in cartesian equations.

Arts and entertainment

• In art,

• J, the pseudonym of Indian artist Jeyaraj

• In movies and television,

• J, an antagonist in the anime series Bobobo
• Agent J, a character in the Men in Black films portrayed by Will Smith
• J, a pokemon hunter that Ash, Brock, and Dawn met on the way to Floaroma Town

• In music,

• J. Mascis, guitarist and singer of Dinosaur Jr.
• J (singer), a K-pop singer
• J (musician), a Japanese musician
• J Dilla, a hip-hip musician and producer
• J Records, a record label
• J-Zone, a hip-hop musician
• Jay-z, a hip-hop musician

Other uses

• In radio, the NATO J band ranges from 10 to 20 GHz.
• "J" can be short for "joint", a hand-rolled cigarette made with cannabis.
• J is a psychedelic phenethylamine; see J (psychedelic).
• J is the international license plate code for Japan.
• J is the postal code for the western and northern regions of Quebec.
• On the New York City Subway system, J is a rapid transit service running from Downtown Manhattan to Jamaica; see J (New York City Subway service).
• J is a German mintmark which stands for the city of Hamburg.
• In judicial reports, when post-fixed to a surname, 'J' indicates that the named person is a Judge. In formal language it is pronounced 'Mister Justice' or 'Justice'. E.g. 'Smith J' refers to Judge Smith, and when read aloud is pronounced 'Justice Smith'.
• J is a type of sail boat class, i.e. J/24.
• J is Internet/SMS slang for "Joking".

See also

• JJ
• JJJ