All articles starting with U
6,146 articles
Underwater glider
An underwater glider is an autonomous underwater vehicle that propels itself by changing buoyancy, using wings to glide slowly through the ocean and measure temperature and salinity for months.
Underwater habitat
An underwater habitat, or undersea habitat, is a pressurized seafloor structure where people live and work underwater for extended periods, entering through a moon pool.
Underwater hockey
Underwater hockey (Octopush), invented at Southsea, England in 1954 by Alan Blake, is a CMAS-governed pool sport where six-a-side teams push a 3-lb puck with short sticks while breath-holding; average submersion is about 11 seconds.
Underwater Paradise Aquarium
Underwater Paradise Aquarium (水中楽園Aquarium) is a goldfish-focused public aquarium at the Tokinosumika resort in Gotenba, Shizuoka, Japan, displaying about 200 species and 4,500 goldfish; distinct from the unrelated Aquarium Paradise in Bengaluru, India.
Underwater photography
Underwater photography is the practice of taking photographs beneath the water's surface, pioneered by William Thompson in 1856 and advanced by Louis Boutan's first diving photographs in 1893.
Underwater robot swarm
An underwater robot swarm is a group of autonomous underwater vehicles that coordinate on shared missions through local sensing and communication rather than centralized control.
Underwater sports
Underwater sports: disciplines performed under water, governed mainly by CMAS (founded 1959, Cousteau first president), including finswimming, freediving, underwater rugby, hockey, spearfishing, and orienteering; at The World Games since 1981.
Underwater vehicle docking
Underwater vehicle docking is the process by which an autonomous underwater vehicle navigates to and couples with an underwater station to recharge, transfer data, and await its next task.
Underwater wireless optical communication
Underwater wireless optical communication, also called underwater optical wireless communication (UOWC), uses blue-green lasers or LEDs to send data underwater at gigabit rates over roughly 100 meters.
Underwear
Underwear: clothing worn next to the skin under outer clothes, also called undergarments or lingerie. Covers history from 17th-century linen underpants to corsets, thongs, period underwear, and modern moisture-managing fabrics.
Underwear fetishism
Underwear fetishism is sexual arousal focused on undergarments, a form of fetishism; it is fetishistic disorder under DSM-5/ICD only when recurrent over 6 months and causing distress or impairment.
Underweight
Underweight: body weight below the healthy range, defined as BMI under 18.5 kg/m² in adults (WHO grades thinness below 17.0) and BMI below the 5th percentile in children; a screening-based nutritional status with defined pediatric faltering-weight criteria.
Underweight in adults
Underweight in adults: BMI below 18.5 kg/m2 per WHO, CDC, and ICD-11 code 5B54. Covers thinness grades, health risks, MUAC screening, NICE nutrition support criteria, and US and global prevalence trends.
Underwood Tariff
The Underwood Tariff, formally the Revenue Act of 1913, was a US law enacted October 3, 1913 that sharply cut import duties and imposed the first federal income tax.
Underworld
Underworld: the mythological realm of the dead, as in the Greek house of Hades, the Egyptian Duat, and the Mesopotamian netherworld; distinguished from hell by receiving all the dead, with punishment or reward as later elaborations.
Underworld (1927 film)
Underworld (1927) is a silent American gangster film directed by Josef von Sternberg for Paramount, starring George Bancroft, Evelyn Brent, and Clive Brook, from Ben Hecht's Oscar-winning story; widely cited as the first major Hollywood gangster film.
Underworld (2003 film)
Underworld is a 2003 action-horror film directed by Len Wiseman, starring Kate Beckinsale as the vampire warrior Selene, who protects a human doctor during a secret war with werewolves.
Underworld (band)
Underworld: British electronic band of Karl Hyde and Rick Smith (with DJ Darren Emerson 1991-2000), known for dubnobasswithmyheadman (1994), Born Slippy.Nuxx from Trainspotting, and the London 2012 Olympics opening ceremony.
Underworld (film series)
Underworld is an American action-horror film series of five movies released between 2003 and 2016. It chronicles a secret war between aristocratic vampires and Lycans.
Underworld U.S.A.
Underworld U.S.A. is a 1961 Samuel Fuller crime film, also called Underworld, U.S.A., starring Cliff Robertson as Tolly Devlin, a safecracker avenging his father's murder by infiltrating a crime syndicate; based on Joseph F. Dineen's articles, released by Columbia Pictures.
Underworld Vision of an Assyrian Prince
The Underworld Vision of an Assyrian Prince, also called the Vision of Kummâ, is a Neo-Assyrian text in which the prince Kummâ dreams of the Mesopotamian underworld.
Underworld: Awakening
Underworld: Awakening, also known as Underworld 4, is a 2012 American action horror film starring Kate Beckinsale, the fourth in the Underworld series and the first in 3-D.
Underworld: Blood Wars
Underworld: Blood Wars (2016) is the fifth Underworld film, directed by Anna Foerster, starring Kate Beckinsale as Selene fighting Lycans and a betraying vampire faction; it earned $81.2 million worldwide on a $35 million budget.
Underworld: Evolution
Underworld: Evolution is a 2006 American action-horror film, the second installment of the Underworld franchise, directed by Len Wiseman and starring Kate Beckinsale as the vampire Selene.
Underworld: Rise of the Lycans
Underworld: Rise of the Lycans (2009) is the third Underworld film and a prequel directed by Patrick Tatopoulos, starring Michael Sheen, Bill Nighy, and Rhona Mitra, telling how Lucian's revolt against vampire king Viktor began the Vampire-Lycan war.
Underwriting
Underwriting is the business of pricing and accepting financial risk for a fee: insurers set premiums, investment banks handle new share issues, and lenders evaluate borrowers.
Undescended testicle, unilateral
Undescended testicle, unilateral (unilateral cryptorchidism, ICD-11 LB52.1): one testis fails to descend into the scrotum. Treated by orchidopexy before 12–18 months; fertility rate reduced but paternity preserved; elevated testicular cancer risk.
Undifferentiated carcinoma of esophagus
Undifferentiated carcinoma of esophagus (WHO 8020/3), a rare aggressive esophageal cancer lacking squamous, glandular, and neuroendocrine differentiation, often SMARCA4/SMARCA2-deficient, associated with Barrett esophagus and median survival 2.60 months.
Undifferentiated carcinoma of stomach
Undifferentiated carcinoma of the stomach, also called undifferentiated gastric carcinoma, is a rare, highly aggressive stomach cancer whose cells show no glandular, squamous, or neuroendocrine differentiation under the microscope.
Undifferentiated carcinoma of the corpus uteri
Undifferentiated carcinoma of the corpus uteri, also called endometrial undifferentiated carcinoma (UEC), is a rare, aggressive uterine cancer of undifferentiated cells, first distinctly defined in 2005.