All articles starting with O
9,097 articles
On-Line Encyclopedia of Integer Sequences
The On-Line Encyclopedia of Integer Sequences (OEIS), also called Sloane's OEIS, is a free online database of integer sequences, online since 1996 and holding over 400,000 entries.
On-load tap changer
An on-load tap changer (OLTC) is a switching device in a power transformer that regulates output voltage in discrete steps while the transformer remains energized and carrying load.
On-off keying
On-off keying (OOK) is the simplest form of amplitude-shift keying, transmitting bits by switching a carrier on and off, used in keyless entry and optical links.
On-orbit satellite servicing
On-orbit satellite servicing is the refueling, repair, and upgrading of satellites in orbit, from the 1984 SolarMax repair and Hubble missions to commercial robotic craft like MEV-1.
On-policy distillation
On-policy distillation is a post-training method for language models in which the student generates its own rollouts and a stronger teacher grades every token, combining reinforcement learning's on-policy training with dense distillation supervision.
On-policy interpretability of reasoning models
On-policy interpretability of reasoning models is the practice of monitoring a reasoning model's internal states and chain of thought to detect hidden objectives and unfaithful reasoning.
On-premises software
On-premises software, sometimes called on-prem, is software an organization installs and runs on its own servers, with internal IT staff handling hardware, updates, and security, in contrast to cloud-based SaaS.
On-site electrochemical H2O2 synthesis
On-site electrochemical H2O2 synthesis produces hydrogen peroxide at the point of use, typically via the two-electron oxygen reduction of oxygen and water with renewable electricity, avoiding hazardous transport of centralized peroxide.
On-stack replacement
On-stack replacement is a virtual machine technique for switching a running function between compiled versions of its code while it executes, used in Java HotSpot and Google V8.
On-surface synthesis
On-surface synthesis is a method that carries out organic chemical reactions on solid surfaces, typically under ultra-high vacuum, to build atomically precise nanostructures like graphene nanoribbons.
On-the-fly probability enhanced sampling
OPES (On-the-fly Probability Enhanced Sampling) is an enhanced sampling method for molecular dynamics simulations that builds a bias potential on the fly, introduced by Michele Invernizzi and Michele Parrinello in 2021.
On-the-job search
On-the-job search is the search by employed workers for alternative or additional employment while remaining in their current job, making up over 60 percent of all job searchers.
On-the-job training
On-the-job training (OJT) is training delivered at the workplace during productive work, ranging from informal learning by doing to structured programs with instructors and competence testing.
On-water reaction
An on-water reaction is an organic reaction run as an aqueous suspension that proceeds far faster than in organic solvents, a term coined by Barry Sharpless in 2005.
On'yomi (音読み)
On'yomi (音読み) is the Chinese-derived reading of Japanese kanji, opposite the native kun'yomi. Layered borrowings (Go-on, Kan-on, Tō-on) from Middle Chinese explain why one kanji like 行 has several on readings.
On3.com
On3.com is the site of On3 Media, a Nashville sports media company founded by Shannon Terry in 2021 covering college sports, recruiting, the transfer portal, and NIL valuations; it acquired Rivals from Yahoo Sports in 2025.
Ona culture
The Ona culture, in the literature the Ancient Ona culture, was a settled agropastoral culture of the Asmara area, Eritrea, from about 800 to 400 BC.
Ona Enda Aboi Zewge
Ona Enda Aboi Zewge (ʿOna Ǝnda Aboi Zägwe) is a Proto-Aksumite stela-field cemetery on Bieta Giyorgis hill northwest of Aksum, Ethiopia, with over 100 stelae up to 10 m high.
Ona Nagast
Ona Nagast is an archaeological settlement site on the slope of Bieta Giyorgis hill near Aksum, Ethiopia, occupied from Proto-Aksumite times and traditionally the residence of the earliest Aksumite kings.
Ona Therapeutics
Ona Therapeutics SL is a Barcelona biotech founded in 2019 as a spin-off of IRB Barcelona and ICREA; it develops antibody-drug conjugates for treatment-resistant cancers and raised $86.6 million in 2026.
Onaayum Aattukkuttiyum (ஓநாயும் ஆட்டுக்குட்டியும்)
Onaayum Aattukkuttiyum (ஓநாயும் ஆட்டுக்குட்டியும்), aka The Wolf and the Lamb, is Mysskin's 2013 Tamil neo-noir thriller with no songs or heroine, starring Mysskin and Sri, scored by Ilaiyaraaja, acclaimed and cult-status.
Onagawa nuclear power plant
The Onagawa nuclear power plant (女川原子力発電所) is a nuclear station in Onagawa, Miyagi Prefecture, Japan, run by Tohoku Electric Power and known for safely withstanding the 2011 earthquake and tsunami.
Onager
The onager (Equus hemionus), also called the Asiatic wild ass or hemione, is an endangered wild equid of the horse family native to the deserts and steppes of Asia.
Onagraceae
Onagraceae, the evening primrose family (Onagraceae Juss., nom. cons., 1789), a Myrtales family of about 650 species in 22-23 genera, mostly New World herbs and shrubs with 4-merous flowers, inferior ovaries, and viscin-threaded pollen; includes Oenothera, Fuchsia, Clarkia, Epilobium, Ludwigia.
Onaka
Onaka: a name shared by a French surf school in Hendaye, a district of Nago City, Okinawa, a South Dakota community, Onaka Park in Yamatotakada, Arla's 1990 Swedish product, and the Japanese surname 大中.
Ōnakatomi no Yoshinobu
Ōnakatomi no Yoshinobu (大中臣能宣, 921–991) was a Japanese court poet and Shinto official, one of the Thirty-six Poetic Immortals and chief priest of Ise Shrine from 973.
Onake Obavva
Onake Obavva (ಒನಕೆ ಒಬವ್ವ) was a woman of Chitradurga fort in Karnataka who killed Hyder Ali's soldiers with a wooden pestle during his 1779 siege.
Onam (ഓണം)
Onam (ഓണം) is Kerala's annual harvest festival in the month of Chingam (August–September), celebrating the homecoming of King Mahabali and the Vamana legend, with Pookkalam, Onasadya, Vallam Kali, and ten days of festivities; it is Kerala's official state festival since 1961.
Onan
Onan (Hebrew: אוֹנָן) is a figure in Genesis 38, Judah's second son, who died by divine punishment after spilling his seed rather than fathering a child for his dead brother Er through Tamar.
Onartuzumab
Onartuzumab (MetMAb, OA-5D5) is Genentech's humanized monovalent anti-MET monoclonal antibody blocking HGF binding; phase III METLung and later meta-analyses showed no survival benefit in NSCLC, gastric, or colorectal cancer, and it was never approved.