J, or j, is the tenth letter of the English alphabet. J may also refer to: *

Palatal approximant The voiced palatal approximant is a type of consonant used in many spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is ; the equivalent X-SAMPA symbol is j, and in the Americanist phonetic notation i ...

in the International Phonetic Alphabet * J, Cyrillic letter Je

Astronomy

* J, a provisional designation prefix for some objects discovered between May 1 and 15 of a year

Computing

J (programming language) The J programming language, developed in the early 1990s by Kenneth E. Iverson and Roger Hui, is an array programming language based primarily on APL (also by Iverson). To avoid repeating the APL special-character problem, J uses only the ba ...

, successor to APL * J# programming language for the Microsoft .NET Framework *

J operator In computer science, Peter Landin's J operator is a programming construct that post-composes a lambda expression with the continuation to the current lambda-context. The resulting “function” is first-class and can be passed on to subsequent ...

, a programming construct * J (operating system), an operating system for ICL's System 4 series of computers

Genetics and medicine

* Haplogroup J (mtDNA) *

Haplogroup J (Y-DNA) Haplogroup J-M304, also known as J,ISOGG] ''Y-DNA Haplogroup J and its Subclades - 2016'' (2 February 2016). is a human Y-chromosome DNA haplogroup. It is believed to have evolved in the Caucasus or Iran.' The clade spread from there during t ...

* ATC code J ''Antiinfectives for systemic use'', a section of the Anatomical Therapeutic Chemical Classification System

Mathematics

* J, symbol used to denote the

Bessel function Bessel functions, named after Friedrich Bessel who was the first to systematically study them in 1824, are canonical solutions of Bessel's differential equation x^2 \frac + x \frac + \left(x^2 - \alpha^2 \right)y = 0 for an arbitrary complex ...

* ''j'', used as the symbol for the

imaginary unit The imaginary unit or unit imaginary number () is a mathematical constant that is a solution to the quadratic equation Although there is no real number with this property, can be used to extend the real numbers to what are called complex num ...

(

\sqrt

) in fields where ''i'' is used for a different purpose (such as electric current) * ''j'' and ''j²'' (or

\bar

) are also used for the complex cube

roots of unity In mathematics, a root of unity is any complex number that yields 1 when raised to some positive integer power . Roots of unity are used in many branches of mathematics, and are especially important in number theory, the theory of group char ...

* ''j'', a number with the property ''j'' ² = +1, used in the definition of the split-complex numbers * ''j'', the second imaginary unit of a

quaternion In mathematics, the quaternion number system extends the complex numbers. Quaternions were first described by the Irish mathematician William Rowan Hamilton in 1843 and applied to mechanics in three-dimensional space. The algebra of quater ...

* , an index variable in a

matrix Matrix (: matrices or matrixes) or MATRIX may refer to: Science and mathematics * Matrix (mathematics), a rectangular array of numbers, symbols or expressions * Matrix (logic), part of a formula in prenex normal form * Matrix (biology), the m ...

* The

j-invariant In mathematics, Felix Klein's -invariant or function is a modular function of weight zero for the special linear group \operatorname(2,\Z) defined on the upper half-plane of complex numbers. It is the unique such function that is holomorphic a ...

, a modular function

Physics and chemistry

* J,

Joule The joule ( , or ; symbol: J) is the unit of energy in the International System of Units (SI). In terms of SI base units, one joule corresponds to one kilogram- metre squared per second squared One joule is equal to the amount of work d ...

, the SI unit of energy * J, the SI-recommended dimension symbol for

luminous intensity In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the huma ...

, conventionally rendered in a sans-serif typeface * ,

current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ...

second moment of area The second moment of area, or second area moment, or quadratic moment of area and also known as the area moment of inertia, is a geometrical property of an area which reflects how its points are distributed with regard to an arbitrary axis. Th ...

* J, name given by Samuel C. C. Ting for the

J/ψ particle The (J/psi) meson is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as " charmonium" or psions. Th ...

J-coupling In nuclear chemistry and nuclear physics, ''J''-couplings (also called spin-spin coupling or indirect dipole–dipole coupling) are mediated through chemical bonds connecting two spins. It is an indirect interaction between two nuclear spins tha ...

, indirect dipole-dipole coupling between two nuclear spins *

J (element) Iodine is a chemical element; it has Chemical symbol, symbol I and atomic number 53. The heaviest of the stable halogens, it exists at Standard temperature and pressure, standard conditions as a semi-lustrous, non-metallic solid that melts t ...

, atomic symbol of ''Jod'', German for iodine

Music

* J, stage name of Jang Ye-eun, a member of the K-Pop group

STAYC STAYC (; , acronym for Star to a Young Culture) is a South Korean girl group formed by High Up Entertainment. The group is composed of six members: Sumin, Park Si-eun (entertainer), Sieun, Isa, Seeun, Yoon, and J. Mainly produced by K-pop duo ...

J (Korean singer) Chung Jae-young (; born May 2, 1977), better known by the stage names J and J.ae (), is a Korean-American singer based in South Korea. She debuted in 1998 with the album, ''J: Gold''. Early life J was born Chung Jae-young on May 2, 1977. Her ...

, a Korean pop singer *

J (musician) , better known by his stage name J, is a Japanese musician, singer-songwriter and record producer. He is best known as bassist and co-founder of the rock band Luna Sea since 1986. After they disbanded in 2000 he focused on his solo career, for ...

, a Japanese rock musician * J., nickname of American White Zombie guitarist

Jay Yuenger Jay Noel Yuenger also known by the stage name "J.", is an American rock guitarist best known for his work with heavy metal band White Zombie. Career As a teenager, Yuenger's interests quickly progressed from pop to hard rock to hardcore pu ...

*J., stage name of German musician

Jaye Muller Jaye Muller (born Jens Müller) is a German musician and Internet entrepreneur who performed under the name J. in the 1990s, and later in a duo named "Muller and Patton" with American musician Ben Patton and since 2015 under the name "Count Jaye" ...

J Mascis Joseph Donald Mascis Jr. (born December 10, 1965), better known as J Mascis, is an American musician who is the singer, guitarist and main songwriter for the alternative rock band Dinosaur Jr. He has also released several albums as a solo artist a ...

, American singer and guitarist of Dinosaur Jr. *

J Records J Records was an American record label owned and operated by Bertelsmann Music Group until it was transferred to Sony Music Entertainment when they acquired all of BMG's record labels in late 2008 at the end of their merger. It was distribut ...

, a record label

Albums

* ''J'' (Jaehyun album), album by South Korean singer Jaehyun

Songs

* "J", song by Reggie and the Full Effect from the album '' Last Stop: Crappy Town'' * "J", song by Mindless Self Indulgence from the album '' Frankenstein Girls Will Seem Strangely Sexy''

Film and television

* Agent J, a character in the ''Men in Black'' films portrayed by Will Smith * J, an antagonist in '' Bobobo'' * '' Kamen Rider J'', a Japanese movie *J, the production code for the 1964 ''Doctor Who'' serial '' Planet of Giants'' * Serial Designation "J", one of the antagonists from the web series '' Murder Drones'' (2021-2024)

Writers

* J (sometimes given as I), pen name of the Danish novelist Cornelia von Levetzow (1836–1921)

Transportation

* J (Los Angeles Railway) *

J (New York City Subway service) The J Nassau Street Local and Z Nassau Street Express are two rapid transit services in the B Division (New York City Subway), B Division of the New York City Subway. Their route emblems, or "bullets", are colored since they use the BMT Nassau ...

* J Church (San Francisco Muni) * J Line (Los Angeles Metro) * NZR J Class, a 4-8-2 type class of steam locomotive used by New Zealand Railways *

Transilien Line J Transilien Paris-Saint-Lazare is one of the sectors in the Paris Transilien suburban rail network. The trains on this sector depart from Gare Saint-Lazare in central Paris and serve the north and north-west of Île-de-France region with Transilien ...

, a line of the Paris transport network * JRW kinki-J

, the official West Japan Railway Company service symbol for the Bantan Line * Saviem J, also known as the Renault J, a range of medium-duty trucks * "The J", a nickname for the Elgin, Joliet and Eastern Railway, a former railroad

Other uses

* J, slang for

joint (cannabis) A joint is a rolled Cannabis (drug), cannabis cigarette. Unlike commercial tobacco cigarettes, the user ordinarily hand-rolls joints with rolling papers, though in some cases they are machine-rolled. Rolling papers are the most common ro ...

* J, slang for

Air Jordan Air Jordan is a line of basketball and sportswear shoes produced by Nike, Inc. Related apparel and accessories are marketed under Jordan Brand. The first Air Jordan shoe was produced for basketball player Michael Jordan during his time with t ...

shoes * J, slang for a jump shot in basketball * J band (disambiguation) * J (psychedelic), an entactogenic drug * Elgin, Joliet and Eastern Railway, a Chicago railway sometimes referred to as "The J" * J, the international license plate code for Japan * J, the

Canadian postal code A Canadian postal code () is a six-character string that forms part of a postal address in Canada. Like British, Irish, Dutch, and Argentinian postcodes, Canada's postal codes are alphanumeric. They are in the format ''A1A 1A1'', where '' ...

for the western and northern regions of Quebec * J, German

mint mark A mint mark is a letter, symbol or an inscription on a coin indicating the mint where the coin was produced. It is distinct from a mintmaster mark, the mark of the mintmaster. History Mint marks were first developed to locate a problem. If a co ...

for the city of Hamburg * J abbreviation for

Jahwist The Jahwist, or Yahwist, often abbreviated J, is one of the most widely recognized sources of the Pentateuch (Torah), together with the Deuteronomist, the Priestly source and the Elohist. The existence of the Jahwist text is somewhat controver ...

, one of the hypothesized major authors of the Torah * J, an abbreviated title of a High Court judge (in Law Reports, etc.), e.g. Bloggs J * '' J. The Jewish News of Northern California'', a weekly newspaper serving the Jewish community in Northern California * J, the narrator of Jerome K. Jerome's novel ''

Three Men in a Boat ''Three Men in a Boat (To Say Nothing of the Dog)'',The Penguin edition punctuates the title differently: ''Three Men in a Boat: To Say Nothing of the Dog!'' published in 1889, is a humorous novel by English writer Jerome K. Jerome describing ...

'' * J., Jezper Söderlund, the trance artist * Lamborghini Aventador J, a 2012 Lamborghini supercar * ''J'' (novel), a 2014 novel by Howard Jacobson * ''ʲ'', the symbol for Palatalization in the IPA * Juliet, sometimes used as the unofficial military time zone code for local time * '' "J" Is for Judgment'', the tenth novel in Sue Grafton's "Alphabet mystery" series, published in 1993 * Guy Big J, range of trucks produced by Guy Motors of England between 1964 and 1978 * code for

academic journal An academic journal (or scholarly journal or scientific journal) is a periodical publication in which Scholarly method, scholarship relating to a particular academic discipline is published. They serve as permanent and transparent forums for the ...

in the reference section of an academic work