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Trigonodus
Trigonodus (Sandberger in Alberti, 1864) is an extinct Triassic trigoniid bivalve genus, type species T. sandbergeri, a brackish-marine soft-bottom dweller linking marine trigoniids and freshwater unionoids; distinct from conodont and shark homonyms.
Trigonometric functions
Trigonometric functions, also called circular functions, relate an angle to side ratios of a right triangle; the six are sine, cosine, tangent, secant, cosecant, and cotangent.
Trigonometric levelling
Trigonometric leveling is a surveying method that determines the difference in elevation between two points from a vertical angle and a distance, used in variable terrain where fewer instrument setups are needed.
Trigonometric parallax
Trigonometric Parallax is an astrometric method measuring a star's angular shift as Earth orbits, forming the first step of the cosmic distance ladder.
Trigonometry
Trigonometry is the branch of mathematics that studies the relationships between the angles and sides of triangles, and the sine, cosine, and tangent functions expressing them.
Trigun (トライガン)
Trigun (トライガン) is Yasuhiro Nightow's sci-fi western manga about pacifist gunslinger Vash the Stampede, wanted for 60 billion double dollars. Serialized 1995–2007 as Trigun and Trigun Maximum; adapted into the 1998 Madhouse anime, the 2010 film Badlands Rumble, and the 2023 CGI reboot Trigun Stampede.
Trigun: Badlands Rumble (劇場版TRIGUN -Badlands Rumble-)
Trigun: Badlands Rumble (劇場版TRIGUN -Badlands Rumble-) is a 2010 Madhouse anime film directed by Satoshi Nishimura, an original story placing Vash the Stampede against thief Gasback in Macca City, set between episodes 10 and 12 of the 1998 Trigun anime.
Trihalomethane
Trihalomethanes (THMs) are halogen-substituted single-carbon compounds of the form CHX₃, formed when drinking water is chlorinated and regulated in the United States as a group of four compounds at 80 µg/L.
Triheptanoin
Triheptanoin, sold as Dojolvi and developed by Ultragenyx as UX007, is a synthetic odd-chain triglyceride approved in 2020 to supply calories and fatty acids in long-chain fatty acid oxidation disorders.
Trihexyphenidyl
Trihexyphenidyl (Artane) is a synthetic antimuscarinic anticholinergic drug marketed in 1949 for Parkinson's disease, used for parkinsonism, drug-induced extrapyramidal symptoms, and off-label dystonia, with euphoric effects and misuse potential.
Triiodothyronine
Triiodothyronine (T3, liothyronine as drug), the biologically most active thyroid hormone, discovered 1952 by Gross and Pitt-Rivers, mainly generated from T4 by deiodinases, and used in hypothyroidism treatment.
Triisobutylaluminium
Triisobutylaluminium (TiBA, TIBA) is a pyrophoric, clear, colorless organoaluminium compound made by the direct Ziegler synthesis and used as a Ziegler–Natta cocatalyst, a selective reducing agent, and the precursor to DIBAL-H.
Triisopropylsilyl protection
Triisopropylsilyl (TIPS) protection converts alcohols or terminal acetylenes into ethers or alkynes bearing the triisopropylsilyl group; its steric bulk makes TIPS ethers the most base-stable of the common silyl protecting groups, cleaved with fluoride.
Trijet
A trijet is an aircraft powered by three jet engines, typically two under the wings and one in the tail, prominent in commercial aviation from the mid-1960s to the 1980s.
Trijumf
Trijumf (Croatian Triumph) is a Croatian trick-taking card game of the madrasso family, for 2 or 4 players with a 40-card Trieste deck, Briscola card values, king-horse declarations, and a 401-point target.
Trika
Trika (त्रिक, "threefold"), often imprecisely called Kashmir Shaivism, is a non-dualistic tantric Shaiva tradition flourishing in Kashmir from about 900 CE, teaching the co-essentiality of the individual, Shakti, and Shiva.
Trikatu curna (trikatu cirma)
Trikatu curna (Trikatu Cūrṇa), also called trikatu churna, is an Ayurvedic powder of equal parts long pepper, black pepper, and ginger, used for digestion and studied as a piperine-based bioavailability enhancer.
Trike
Trike (board game) is a 2020 combinatorial abstract strategy game by Alek Erickson, also called トライク; two players move a shared pawn on a triangular grid, dropping checkers, and score around the trapped pawn.
Triketone
A triketone, also called a trione, is an organic compound with three ketone groups that can tautomerize to enol forms, chelate metals, and underlie HPPD-inhibiting herbicides like mesotrione.
Trikka
Trikka (Τρίκκα, Tricca): name of two ancient Greek places, a Thessalian city at modern Trikala, Homeric and center of Asclepius worship, and an unlocated early settlement of Messenia.
Trikomia 3
Trikomia 3 (Τρικωμία) is an unlocated ancient Phrygian settlement, probably between Dorylaion and Pessinous in Turkey, attested as Tricomia on the Peutinger table and in Ptolemy; Ramsay's proposed identity with Troknades is unproven.
Trikorynthos
Trikorynthos (Τρικόρυνθον), also Tricorynthus, an ancient deme of Attica in the Marathon plain near Kato Souli, Greece; member of the Attic tetrapolis, tribe Aiantis, with a rubble fort on Stavrokoraki hill.
Trikweze Bridges
Trikweze Bridges (born 2000) is an NFL cornerback from Lanett, Alabama; Oregon/Florida; drafted 256th overall by the Chargers in 2025, claimed by Dallas, 1 INT in 2025, Bengals practice squad 2026.
Trilaciclib
Trilaciclib (Cosela) is a CDK4/6 inhibitor infused before chemotherapy to protect bone marrow in extensive-stage small-cell lung cancer; FDA approved February 2021, first myelopreservation drug.
Trilateral Commission
The Trilateral Commission, or Trilateralism, is a private, invitation-only forum of about 400 leaders from North America, Europe, and Asia-Pacific, founded by David Rockefeller in 1973.
Trilateration
Trilateration is a positioning method that determines an unknown location by measuring distances to three or more known reference points rather than angles, and underpins satellite navigation.
Trilayer graphene
Trilayer graphene is a stack of three single-atom-thick carbon sheets whose electronic behavior depends on stacking: ABA is a semimetal, while ABC is a tunable semiconductor.
Trilby
Trilby: a soft felt hat with a short (under 2 inch) brim angled down at the front and up at the back, shorter crown than a fedora, named after du Maurier's 1894 novel Trilby and its stage adaptation; chiefly British, casual wear.
Trilby (novel)
Trilby (1894) is George du Maurier's serialized novel of hypnotist Svengali and artist's model Trilby O'Ferrall in bohemian Paris; a Victorian bestseller that gave English the words Svengali and the trilby hat.
Trilce
Trilce is the second book of poetry by the Peruvian poet César Vallejo, published in Lima in 1922; its radical language made it a foundational work of the Spanish-language avant-garde.