All articles starting with R
22,461 articles
Ritonavir
Ritonavir (ABT-538), an Abbott HIV protease inhibitor approved by the FDA in 1996 (Ki 0.015 nM), now used mainly at 100 mg doses as a CYP3A4/P-gp pharmacokinetic booster for HIV drugs and as the booster in Paxlovid.
Ritornello
Ritornello (Italian, "little return"): a recurring instrumental refrain, chiefly the orchestral passage alternating with solo episodes in Baroque concerto form (ABACA), also used in arias; returns may occur in non-tonic keys, distinguishing it from the rondo.
Ritsuryō system
The Ritsuryō system (律令制) was ancient Japan's centralized political order, based on ritsuryō codes adapted from Tang China and essentially completed by the Taihō Code of 701.
Ritter reaction
The Ritter reaction is an acid-promoted organic method that converts a nitrile plus a carbocation source, usually an alcohol or alkene, into an N-substituted amide.
Ritter Sport
Ritter Sport is a German family-owned chocolate brand (Alfred Ritter GmbH & Co. KG), founded 1912, known for square bars, colorful packaging, 100% Rainforest Alliance certified cocoa since 2018, and 712 million euros in 2025 sales.
Rittium
Rittium (Ῥίττιον), a Roman auxiliary fort on the Danube limes in Pannonia Inferior at Gradina near Surduk, Serbia; garrisoned by ala I Augusta Ituraeorum and others, later equites Dalmatae, with a 2nd-century naval station role.
Ritu Arya
Ritu Arya is a British actress and drummer, member of the band KIN. Known for Lila Pitts in The Umbrella Academy, Inspector Urvashi Das in Red Notice, BIFA-nominated Lena in Polite Society, and journalist Barbie in Barbie; leads BBC's The Split Up as Aria Kishan.
Ritu Khanduri Bhushan
Ritu Khanduri Bhushan is an Indian Bharatiya Janata Party politician serving as the first woman Speaker of the Uttarakhand Legislative Assembly, after winning the Kotdwar seat in 2022.
Ritu Phogat
Ritu Phogat, "The Indian Tigress" (born 1994, Balali, Haryana), Indian wrestler and ONE Championship MMA fighter; 2016 Commonwealth Wrestling gold, U23 Worlds silver; pro MMA record 7-5, 2021 atomweight Grand Prix finalist.
Ritu Raman
Ritu Raman is an American mechanical engineer at MIT who works on biohybrid robotics and 4D tissue engineering, building machines powered by living muscle; she received the Presidential Early Career Award in 2025.
Ritu Tawde
Ritu Tawde (रितू तावडे), BJP politician and three-term Ghatkopar corporator, was elected unopposed as Mumbai's 78th mayor on 11 February 2026, the city's eighth woman mayor and the BJP's first since 1982–83.
Ritu Varma
Ritu Varma (born 1990, Hyderabad) is an Indian actress in Telugu and Tamil cinema, known for Anukokunda and Pelli Choopulu (2016), which won her the Nandi Award for Best Actress and Filmfare Critics Award for Best Actress – South.
Ritual
Ritual is a predefined sequence of rigid, formal, repeated ceremonial acts prescribed by tradition or religious decree, found in all known societies and often marking transitions between life stages.
Ritual behavior in animals
Ritual behavior in animals, or ritualization, is the evolutionary process by which ordinary actions like digging, locomotion, or lip-pulling become stereotyped communication signals such as threat displays, studied since Tinbergen's four-step model.
Ritual of Embalming Papyrus
The Ritual of Embalming is the principal surviving ancient Egyptian ritual text for embalming a human body, preserved in hieratic papyrus copies of the Roman period from Thebes.
Ritual purification
Ritual purification, also called ritual cleansing or purity rite, is the religious use of rites like ablution and immersion to remove impurity, in Judaism, Islam, Shinto, and other traditions.
Ritual Reform of the Jiajing Emperor
The Ritual Reform of the Jiajing Emperor (嘉靖更定祀典) was a sweeping revision of the Ming dynasty's state sacrificial system under Emperor Jiajing, launched after the Great Rites Controversy.
Ritual washing in Judaism
Ritual washing in Judaism, also called ablution in Judaism, ranges from hand-washing to full-body immersion in a mikveh, by which Jews remove ritual impurity or mark holiness.
Rituals Cosmetics
Rituals Cosmetics is an Amsterdam-based home and body cosmetics brand founded by Raymond Cloosterman in 2000, with nearly 1,500 boutiques in 33 countries and 2025 revenue of €2.43 billion.
Rituals of Signs and Transformations
Rituals of Signs and Transformations (Tuqus al-isharat wa-l-tahawwulat) is a 1994 play by the Syrian playwright Sa'd Allah Wannus, set in 1880s Damascus during a feud between the city's mufti and the leader of the ashraf.
Rituparna Sengupta
Rituparna Sengupta (ঋতুপর্ণা সেনগুপ্তা), born 1970 or 1971 in Calcutta, is a Bengali film actress and producer; debut Shwet Patharer Thala, National Award winner for Dahan, over 100 films.
Rituparno Ghosh (ঋতুপর্ণ ঘোষ)
Rituparno Ghosh (ঋতুপর্ণ ঘোষ), 1963–2013, Bengali film director from Kolkata; nearly 20 films, a dozen National Film Awards, Unishe April breakthrough, queer trilogy, first queer star of Bengal.
Ritusamhara
Ritusamhara (ऋतुसंहारम्), also rendered "Garland of Seasons," is a short Sanskrit lyric poem attributed to Kalidasa, describing six Indian seasons and the love-play they stir in young couples.
Rituximab
Rituximab, sold under names Rituxan and MabThera, is a chimeric mouse/human monoclonal antibody used to treat B-cell cancers and various autoimmune conditions. It received FDA approval in 1997.
Ritvad
Ritvad (रीतिवाद), the Riti school, is a school of Sanskrit poetics founded by the Kashmiri scholar Vamana, holding that style is the soul of poetry.
Ritwik Ghatak (রিত্বিক কুমার ঘটক)
Ritwik Kumar Ghatak (রিত্বিক কুমার ঘটক, 1925–1976), Bengali filmmaker born in Dhaka, Communist Party and IPTA member, chronicler of the 1947 Partition of Bengal; made eight features including Meghe Dhaka Tara, Subarnarekha, and Titash Ekti Nadir Naam.
Ritz Correia
Ritz Correia (Maritza Correia-McClendon), born 1981 in San Juan, Puerto Rico, is an American swimmer, first African-American woman on a US Olympic swim team, 2004 Athens 4x100m freestyle relay silver medalist and Georgia Bulldogs record holder.
Ritz Crackers
Ritz Crackers, also RITZ, is a round buttery snack cracker brand introduced by Nabisco in 1934 and owned by Mondelēz International; seven perforations, scalloped edge, once 29 million baked daily.
Ritz method
The Ritz method, also known as the Rayleigh–Ritz method, is a numerical technique that approximates solutions of variational and boundary value problems by minimizing a functional over trial functions.
Ritzing
SC Ritzing (Sportclub Ritzing), Austrian football club founded 1963 in Ritzing, Burgenland; blue-yellow, Sonnenseestadion. Regionalliga Ost champion 2014/15 but denied license; withdrew from adult football 2024, second insolvency.