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Caligula
Caligula (Gaius Julius Caesar Augustus Germanicus), Roman emperor 37-41 CE, nicknamed 'little boot' as a child; first Roman emperor assassinated; reign known mainly through hostile later sources such as Suetonius and Cassius Dio, now heavily reassessed.
Călin Georgescu
Călin Georgescu (born 1962), Romanian far-right independent politician; won the annulled first round of the 2024 presidential election with 22.94%, was barred from the 2025 rerun, and faces multiple criminal cases including fraud and promoting legionary ideology.
Caliph of the Islamic State
The caliph of the Islamic State is the self-proclaimed supreme religious and political leader of ISIS (ISIL), a title the group has claimed since declaring a caliphate in June 2014.
Caliphate
A caliphate, also known as khilafah (خِلافة), is a Muslim state combining political and religious authority under a caliph, established in 632 and abolished in 1924.
Caliphate of Córdoba
The Caliphate of Córdoba (الخلافة الأموية في قرطبة) was the Umayyad Muslim state in al-Andalus, with its capital at Córdoba, existing from 929 to 1031.
Caliphate of Hamdallahi
The Caliphate of Hamdallahi, also called the Massina Empire or Laamu Diina, was a Fulbe theocratic state in the Inland Niger Delta of Mali founded in 1818.
Calixto García
Calixto García Íñiguez was a Cuban major general who fought in all three of Cuba's wars of independence against Spain and commanded Cuban forces at Santiago de Cuba in 1898.
Calixto Romero Hernández
Calixto Romero Hernández was a Spanish-born merchant who founded a straw-hat trading business in Catacaos, Piura, Peru, in 1888, growing into Grupo Romero, one of Peru's largest family-controlled groups.
Call a spade a spade
Call a spade a spade: English idiom for blunt, plain speaking, from a Greek saying about figs and troughs mistranslated by Erasmus and fixed in English by Udall in 1542; unrelated to the 1928 racial slur.
Call centre
A call center, also known as a call center or answering service, is an office operation handling large volumes of customer calls, with over 50 million agents worldwide.
Call girl
A call girl, or escort prostitute, is a female sex worker who arranges meetings with clients by phone or internet rather than working from a fixed location.
Call option
A call option, also known as a long call, gives its buyer the right to buy an asset at a fixed strike price before expiration, for a premium.
Call sign
Call sign: unique 3-7 character alphanumeric identity assigned to a radio station under ITU Radio Regulations Article 19 and Appendix 42; US broadcast K/W Mississippi split, amateur sequential, vanity, and special event systems.
Call signs in Canada
Call signs in Canada: ISED-assigned identifiers using ITU blocks. Amateur signs use VE, VA, VO, VY provincial prefixes; broadcasting uses CF, CH, CI, CJ, CK, with CB reserved for CBC stations.
Call signs in Korea
Call signs in Korea (호출부호): ITU prefixes HL, DS/DT, 6K–6N for South Korea and HM, P5–P9 for North Korea; CRMS assigns amateur calls in application order; 24,320 licensees as of September 2026.
Call signs in North America
Call signs in North America: US broadcast K/W signs split at the Mississippi River, Canadian CF/CH/CI/CJ/CK (CB for CBC) signs, and Mexican XE/XH signs, all under ITU Article 19 allocations.
Call signs in Russia
Call signs in Russia: identifiers formed from ITU series RAA–RZZ and UAA–UIZ under Ministry order No. 4 of 2012; R-prefixes need one character, U-series two; digit-letter codes assign call signs by federal subject.
Call to action (marketing)
A call to action (CTA) is a word, phrase, or button in marketing material, such as "Buy Now," that tells the audience what to do next.
Call to the bar
Call to the bar, or being called to the bar, is admission as a barrister, conferred by an Inn of Court in England and Wales after academic, vocational, and qualifying-session requirements, and by provincial law societies in Canada; distinct from US bar admission.
Calla Walsh
Calla Mairead Walsh (born 2004) is an American activist from Cambridge, Massachusetts, once a Markeyverse organizer for Ed Markey, later co-founder of Palestine Action US, arrested in the 2023 Merrimack Four Elbit action, now based in Beirut contributing to Iranian state media.
Callable bond
A callable bond is a bond that gives its issuer the right to redeem it before maturity at pre-agreed dates and prices, usually to refinance when rates decline.
Calles Law
The Calles Law (Ley Calles) was a 1926 Mexican law, promoted by President Plutarco Elías Calles, that penalized violations of the Constitution's anticlerical articles and triggered the Cristero War.
Callicrates of Samos
Callicrates of Samos, also known as Kallikrates, was a Greek admiral who served as supreme commander of the Ptolemaic navy for about twenty years under Ptolemy II.
Callie Barr
Callie Barr is an American Democratic politician from Traverse City, Michigan, the 2026 Democratic nominee for the U.S. House in Michigan's 1st District, facing incumbent Jack Bergman in a rematch of their 2024 race.
Callie V. Granade
Callie V. Granade is an American jurist, a federal district judge in Alabama appointed by George W. Bush, known for striking down the state's same-sex marriage ban in 2015.
Calligraphy
Calligraphy, from Greek kallos and graphein, is the art of decorative writing executed stroke by stroke. Covers Arabic (UNESCO-inscribed 2021), Chinese, Japanese, and Persian traditions, tools like the qalam, and modern calligraffiti.
Calling of the Varangians
The Calling of the Varangians (Призвание варягов) is the chronicle account of Slavic and Finnic tribes inviting the Varangian prince Rurik and his brothers to rule them, dated 862.
Callinicus I
Callinicus I (Greek: Kallinikos, Καλλίνικος) was Ecumenical Patriarch of Constantinople from 693 to 705, remembered for his violent deposition by the restored emperor Justinian II, who had him blinded and exiled to Rome.
Callinicus II
Callinicus II (Καλλίνικος Β΄), known as the Acarnanian, was Ecumenical Patriarch of Constantinople who served three separate terms between 1688 and his death in office in 1702.
Callinicus III
Callinicus III (Καλλίνικος Γ΄), born Konstantinos Mavrikios, was Ecumenical Patriarch of Constantinople from January to July 1757, born and died at Zagora on Mount Pelion.