All articles starting with X
1,563 articles
XK aprosencephaly syndrome
XK aprosencephaly syndrome (Garcia-Lurie syndrome, XK syndrome) is an extremely rare autosomal recessive cerebral malformation with absence of the telencephalon and diencephalon, oculo-facial anomalies, limb defects, and anal atresia; OMIM 207770.
Xkcd
xkcd (xkcd.com) is a stick-figure webcomic of romance, sarcasm, math, and language by Randall Munroe, running since 2005; known for 'Time', 'Duty Calls', What If? books, and CC BY-NC 2.5 licensing.
XKeyscore
XKeyscore is a search and analysis system of the US National Security Agency for intercepted internet content and metadata, disclosed in 2013 via slides leaked by Edward Snowden.
XL Recordings
XL Recordings: British independent record label founded 1989 in London by Richard Russell, Tim Palmer, and Nick Halkes; Beggars Group subsidiary (51% since 2024); home to Adele, Radiohead, The Prodigy, Fontaines D.C.
Xl550
Xl550 is esaxerenone (CS-3150), a nonsteroidal mineralocorticoid receptor antagonist discovered by Exelixis and approved in Japan (2019) for hypertension and studied in diabetic kidney disease.
XLA (Accelerated Linear Algebra)
XLA (Accelerated Linear Algebra) is a machine learning compiler that optimizes linear algebra computations for speed and memory, compiling models from TensorFlow, JAX, and PyTorch for CPUs, GPUs, and TPUs.
Xlife Surf School
Xlife Surf School is a surf school at Praia do Cabedelo, Viana do Castelo, Portugal, founded by PE teachers Jorge Pereira and Rui Silva; group lessons max 6 students, €28 for 2 hours, rentals and kids' lessons from age 6.
xLight
xLight is an American startup founded in 2021 in Palo Alto, California, developing particle-accelerator-driven free-electron lasers as shared EUV light sources for semiconductor lithography, with its first system under construction in New York.
XLM-R
XLM-R, or XLM-RoBERTa, is a multilingual masked language model introduced by Alexis Conneau and colleagues at Facebook AI in 2019, applying the RoBERTa recipe to 100 languages for cross-lingual transfer.
Xlov
Xlov (엑스러브, XLOV) is a four-member multinational K-pop boy group under StrangeLab, formerly 257 Entertainment, that debuted January 7, 2025 with I'mma Be and pioneered a genderless group concept with voguing.
XLR connector
The XLR connector, also known as the Cannon connector or Cannon plug, is a rugged latching three-pin connector used chiefly for balanced analog audio, digital audio, and lighting control.
XLR/SYCP3/FAM9 domain
XLR/SYCP3/FAM9 domain (InterPro IPR006888, Pfam PF04803 Cor1) is a conserved vertebrate protein domain in meiotic chromosome-axis proteins including SYCP3, XLR, XMR, FAM9, and Sly, tied to synaptonemal complex function and fertility.
XLR81
The XLR81 is a gas-generator liquid rocket engine built by Bell Aerosystems that served as the main engine of the Lockheed Agena upper stage from 1959.
xLSTM
xLSTM is a family of recurrent neural network architectures for large language modeling, introduced in May 2024 by Sepp Hochreiter's group at NXAI as a non-Transformer challenger to attention models.
XLZD
XLZD, merging the XENON, LUX-ZEPLIN, and DARWIN collaborations, was formed in 2024 to build a 60–80 tonne liquid-xenon observatory for dark matter, neutrinoless double beta decay, and supernova neutrinos.
XM (Colombian grid operator)
XM, formally XM Compañía de Expertos en Mercados, is the Colombian company that operates the national interconnected system and administers the wholesale electricity market from its Medellín control center.
XM Cyber
XM Cyber is an Israeli cybersecurity company, founded in 2016 in Herzliya by former Mossad director Tamir Pardo, that simulates cyberattacks to find network weaknesses.
XM Satellite Radio
XM Satellite Radio was an American subscription satellite radio service delivering over 100 digital channels; it launched in 2001 and merged with Sirius in 2008.
XM25 CDTE
The XM25 CDTE was a US Army airburst grenade launcher, nicknamed the Punisher, that fired 25 mm programmable rounds to hit enemies behind cover; it was canceled in 2018.
XM274
XM274: American experimental 75mm smoothbore rotating-breech automatic cannon designed by Eugene Stoner, developed from 1973 by ARES Inc ($31m) with AAI ammunition ($28m); vehicle-tested, never entered service; distinct from the M274 mule and 2.75-inch rocket warhead.
Xmas
Xmas is an informal written abbreviation of Christmas; the X is the Greek letter chi, first letter of Christos (Christ), attested in forms from c. 1100 and Xmas from 1721-1755.
XMAS (song)
XMAS (song) is an upbeat Christmas pop song by Kylie Minogue. Released in 2025, it became the UK Christmas Number 1 and her eighth chart-topping single.
XMASS
XMASS, short for Xenon MASSive detector, was a direct dark matter search experiment using 834 kg of liquid xenon deep underground at Japan's Kamioka Observatory, completed in 2024.
xMEMS
xMEMS Labs is a Santa Clara, California semiconductor company, founded in 2018, that develops solid-state silicon microspeakers and a µCooling fan-on-a-chip for earbuds and smart glasses.
XMEN
XMEN disease (X-linked immunodeficiency with magnesium defect, EBV infection, and neoplasia; also MAGT1 deficiency) is a rare X-linked male immunodeficiency causing chronic EBV viremia, lymphoma risk, and low NKG2D, partly treatable with oral magnesium.
XML
XML, or Extensible Markup Language, is a W3C-standardized markup language and subset of SGML designed for ease of implementation and interoperable data exchange on the Web alongside HTML.
XML Encryption
XML Encryption is a W3C standard for encrypting arbitrary data, an XML element, or element content and representing the result in XML; it became a Recommendation in 2002.
XML for Analysis
XML for Analysis (XMLA) is a SOAP-based open protocol published by Microsoft and Hyperion in 2001 for querying OLAP and data mining servers over HTTP, using two methods, Discover and Execute, carrying MDX queries; version 1.1 came in 2002.
XML schema
An XML schema formally describes the structure and datatypes of XML documents, used to validate them; the best-known language is W3C XML Schema (XSD), a 2001 Recommendation.
XML Schema (W3C)
XML Schema, also called XML Schema Definition or XSD, is a W3C schema language defining classes of XML documents through constraints on structure, elements, attributes, and datatypes.