All articles starting with M

Metasurface vortex beam generators

Metasurface vortex beam generators are flat optical devices built from subwavelength meta-atoms that convert incident light into vortex beams carrying orbital angular momentum for communications.

Metasurfaces for spin-Hall effect of light

Metasurfaces for the spin-Hall effect of light are planar arrays of subwavelength optical antennas that greatly amplify the photonic spin Hall effect, first demonstrated in 2013 with V-shaped gold nanoantennas.

Metasyntactic variable

A metasyntactic variable is a placeholder name, such as foo, bar, or baz, used in programming examples and documentation to stand for whatever entity is under discussion.

Metatarsal bones

Metatarsal bones: the five long bones of the forefoot (ossa metatarsi) between tarsals and phalanges; 1st shortest and widest, 2nd longest, bearing 30-50% of gait load; sites of Lisfranc and march fractures.

Metatarsalgia

Metatarsalgia is pain in the ball of the foot around the metatarsal heads, a symptom with primary, secondary, and iatrogenic causes such as Morton's neuroma, stress fracture, and plantar plate tear; treated first conservatively.

Metatarsus valgus

Metatarsus valgus (metatarsal valgus, out-toeing) is a foot anomaly in which the forefoot angles outward relative to the hindfoot with a straight heel; the opposite of metatarsus adductus, coded ICD-11 LB98.21.

Oct 20, 2026

Metatarsus varus

Metatarsus varus, also called metatarsus adductus or adductovarus, is a congenital forefoot deformity with adduction at the tarsometatarsal (Lisfranc) joint; the strict varus form is a tarsometatarsal subluxation that progresses without treatment, unlike flexible metatarsus adductus.

Oct 15, 2026

Metate

A metate is a large stone grinding surface from Mesoamerica, worked with a smaller handstone called a mano to grind maize, cacao, and other foods, still used today.

Metatheria

Metatheria (Marsupialia), infraclass of mammals containing marsupials and extinct stem relatives, sister to Eutheria; split by 160 Ma, oldest fossil Sinodelphys, ~272 living species in South America and Australasia.

Metathesis (linguistics)

Metathesis (linguistics), from Greek 'transposition': a phonological pattern where two sounds reverse order between related word forms, as in Leti ukar/ukra; conditioned by phonology, morphology, speech errors, and historical change.

Sep 29, 2026

Metathesis polymerization

Metathesis polymerization builds unsaturated polymers from olefin monomers using metal carbene catalysts; its main forms are ring-opening ROMP of strained cyclic olefins and ADMET, which releases ethylene.

MetaTrader 4

MetaTrader 4 (MT4) is a retail electronic trading platform for forex and CFD trading, developed by MetaQuotes Software and released in 2005, with automation through its MQL4 language.

Sep 29, 2026

Metatranscriptomics

Metatranscriptomics, including the shotgun metatranscriptomics variant, sequences RNA from an entire microbial community to show which genes are actively expressed, complementing metagenomics, which only inventories genes present.

Metatron (מֶטַטְרוֹן)

Metatron (מֶטַטְרוֹן) is an angel in Jewish rabbinic and mystical tradition, identified with the patriarch Enoch, named in the Talmud, and central to the Hekhalot literature and Kabbalah.

Metatropic dysplasia

Metatropic dysplasia (metatropic dwarfism), a rare autosomal dominant TRPV4-related spondyloepimetaphyseal dysplasia: short limbs and long trunk at birth, progressive kyphoscoliosis reversing proportions, dumbbell long bones, halberd pelvis, adult height 107-135 cm.

Metavalent bonding

Metavalent bonding is a mode of chemical bonding in solids lying between covalent and metallic, where adjacent atoms share about one electron, formalized in 2018.

Metaverse

Metaverse: persistent shared 3D virtual worlds accessed via VR, AR, or screens; term coined in Neal Stephenson's Snow Crash (1992); Meta rebrand 2021; applications in healthcare, education, gaming; interoperability and identity standards remain unsolved.

Metawin Opas-iamkajorn (เมธวิน โอภาสเอี่ยมขจร)

Metawin Opas-iamkajorn (เมธวิน โอภาสเอี่ยมขจร), known as Win Metawin, is a Thai actor born in 1999 who rose to fame as Tine in the 2020 drama 2gether and played Kavin in F4 Thailand.

MetaX (沐曦股份)

MetaX (沐曦股份) is a Shanghai fabless developer of general-purpose GPUs for AI training and inference, founded in 2020 by three former AMD executives and listed on Shanghai's STAR Market in December 2025.

Sep 19, 2026

MetaX Integrated Circuits Shanghai

MetaX Integrated Circuits (沐曦股份), known as Muxi, is a Shanghai fabless developer of general-purpose GPUs for AI training, inference, and graphics, co-founded in September 2020 by three AMD veterans.

Metaxalone

Metaxalone, marketed as Skelaxin since its 1962 United States approval, is a centrally acting muscle relaxant for acute, painful musculoskeletal conditions in adults and patients 13 and older.