XX or xx may refer to: *

20 (number) 20 (twenty) is the natural number following 19 and preceding 21. A group of twenty units is sometimes referred to as a score. In mathematics Twenty is a composite number. It is also the smallest primitive abundant number. The Happy Family o ...

, Roman numeral XX

Film and TV

* ''XX'' (film), a 2017 anthology horror film * "XX", an episode of ''CSI: Crime Scene Investigation'' (season 4) *XX, the production code for the 1969 ''Doctor Who'' serial ''

The Seeds of Death ''The Seeds of Death'' is the fifth serial of the sixth season of the British science fiction television series ''Doctor Who''. Written by Brian Hayles and an uncredited Terrance Dicks and directed by Michael Ferguson, it originally aired in ...

'' * ''XX'' (web series), a 2020 South Korean web series * XX (organization), a fictional organisation in the comic and game ''XIII''

Genetics

*XX sex chromosomes, in the

XY sex-determination system The XY sex-determination system is a sex-determination system present in many mammals (including humans), some insects (''Drosophila''), some snakes, some fish (guppy, guppies), and some plants (''Ginkgo'' tree). In this system, the sex of an ...

XX male syndrome XX male syndrome, also known as de la Chapelle syndrome or 46,XX testicular disorder of sex development (or 46,XX DSD) is a rare intersex condition in which an individual with a 46,XX karyotype develops a male phenotype.updated 2015 In 90 perce ...

, also known as de la Chapelle syndrome, a rare congenital intersex condition resulting in a phenotypical male with two X chromosomes **

XX gonadal dysgenesis XX gonadal dysgenesis is a type of female hypogonadism in which the ovaries do not function to induce puberty in a person assigned female at birth, whose karyotype is 46,XX. Individuals with XX gonadal dysgenesis have normal-appearing external geni ...

, a type of female hypogonadism resulting in non-functioning ovaries *XX sex chromosomes, in the

XO sex-determination system The XO sex-determination system (sometimes referred to as X0 sex-determination system) is a system that some species of insects, arachnids, and mammals (not including humans) use to determine the sex of offspring. In this system, there is only o ...

* a

female An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and ...

, an organism producing ova gametes that fuse with the male gamete during sexual reproduction, typically having two X chromosomes in the XY and X0 sex determination systems

Music

The xx The xx are an English indie rock band from Wandsworth, London, formed in 2005. The band consists of Romy Madley Croft (guitar, vocals), Oliver Sim (bass guitar, vocals), Jamie Smith, also known as Jamie xx (beats, MPC, record production), ...

, an English indie rock band * X_______X (band), an American no wave band

Albums

* ''

Toto XX ''Toto XX: 1977–1997'' is a compilation album by Toto to celebrate their 20th anniversary. The album features rare original demos, outtakes, previously unreleased recordings and live tracks from the band's 20-year career. Despite its being lab ...

'', a 1998 album by Toto * ''XX'' (Mushroomhead album), 2001 * ''xx'' (The xx album), 2009 * ''XX'' (Great Big Sea album), 2012 * ''

XX – Two Decades of Love Metal ''XX – Two Decades of Love Metal'' is a compilation album A compilation album comprises Album#Tracks, tracks, which may be previously released or unreleased, usually from several separate recordings by either one Performing arts#Performers, ...

'', a 2012 compilation album by HIM * ''XX'' (O.A.R. album), 2016 * ''XX'' (Mino album), 2018 * ''XX'', a 2018 album by

Note-oriety Note-oriety is an upper voices a cappella singing group at James Madison University in the United States, founded in 1998 by Kelly Myer and Bonnie Estes. The group sings in and around Harrisonburg, Virginia, tours the east coast and other parts o ...

* ''+ +'' (EP), a 2018 EP, repackaged as '' X' in 2019, by Loona

Songs

* "xx", a song by Hayley Kiyoko from '' Expectations'' * "XX", a song by Feid from '' Ferxxo (Vol 1: M.O.R)''

Organisations

XX Bomber Command The XX Bomber Command was a United States Army Air Forces bomber formation. Its last assignment was with Twentieth Air Force, based on Okinawa. It was inactivated on 16 July 1945. History The idea of basing Boeing B-29 Superfortresses in ...

, an inactive United States Air Force unit *

XX Corps (disambiguation) 20th Corps, Twentieth Corps, or XX Corps may refer to: * XX Corps (German Empire) * XX Corps (Ottoman Empire) * XX Corps (United Kingdom) * XX Corps (United States) * XX Corps (Union Army), a unit in the American Civil War * XX Army Corps (Wehrmach ...

* ''

Legio XX Valeria Victrix Legio XX Valeria Victrix, in English the Twentieth Victorious Valeria Legion, was a legion of the Imperial Roman army. The origin of the Legion's name is unclear and there are various theories, but the legion may have gained its title ''Vale ...

'' or Legion XX, a legion of the Roman Empire

Other uses

* ''XX'' (novel), a 2020 novel by Rian Hughes *

XX System The Double-Cross System or XX System was a World War II counter-espionage and deception operation of the British Security Service (MI5). Nazi agents in Britain – real and false – were captured, turned themselves in or simply announced themselv ...

or Double-Cross System, a British deception operation in the Second World War * ''

Les XX ''Les XX'' ( French; "''Les Vingt''"; ; ) was a group of twenty Belgian painters, designers and sculptors, formed in 1883 by the Brussels lawyer, publisher, and entrepreneur Octave Maus. For ten years, they held an annual exhibition of their a ...

'', a group of twenty Belgian painters *

Dos Equis DOS (, ) is a family of disk-based operating systems for IBM PC compatible computers. The DOS family primarily consists of IBM PC DOS and a rebranded version, Microsoft's MS-DOS, both of which were introduced in 1981. Later compatible systems ...

or XX, a brand of Mexican beer * xx, to express

exponentiation In mathematics, exponentiation, denoted , is an operation (mathematics), operation involving two numbers: the ''base'', , and the ''exponent'' or ''power'', . When is a positive integer, exponentiation corresponds to repeated multiplication ...

in the initial version of the FORTRAN programming language