#Middle Ages

• Abdallah ibn Mohammed — Emir of Cordoba (888–912) during whose reign the administrative foundations for urban and sanitary stability were laid, later enabling the development of major medical and pharmacological centers in Al-Andalus.
• Abubacer — The Latinized name of Ibn Tufayl (Abu Bakr Muhammad ibn Abd al-Malik ibn Tufayl al-Qaysi), an illustrious Arabic philosopher, physician, mathematician, and astronomer from medieval Andalusia (Islamic Spain). He is globally renowned for authoring the philosophical treatise 'Hayy ibn Yaqdhan' (Alive, son of Awake), considered the first philosophical novel in history, a visionary work exploring empiricism, self-taught spiritual enlightenment, and the evolution of the human intellect in total isolation from society.
• Abul Feda — The Latinized name of Abu al-Fida (Isma'il ibn Ali ibn Mahmud al-Ayyubi), a prominent Kurdish prince, historian, geographer, and astronomer of the Ayyubid dynasty, who governed as the emir of Hama (Syria). He is globally recognized for his foundational encyclopedic writings, particularly 'Taqwim al-Buldan' (Sketch of the Countries), a monumental work of descriptive geography, and his universal historical chronicle, which served as essential bridges of knowledge between the medieval East and the European West, his name also being honored by a lunar crater.
• Abul-Faradj — The Arabic name of Bar Hebraeus (Ghiyath al-Din Abu al-Faraj ibn al-Ibri), an illustrious 13th-century Jacobite Christian scholar, physician, philosopher, and theologian, considered one of the last great polymaths of the Christian East. Operating in a context marked by the Mongol invasions, he authored monumental universal chronicles and essential theological treatises in both Syriac and Arabic, preserving a vast amount of knowledge from classical antiquity and Islamic science during a period of profound cultural crisis.
• Adamism — A religious and ascetic doctrine that appeared in the early centuries of Christianity (and was sporadically revived in the Middle Ages by sects such as the Turlupins or Hussites), whose followers, called Adamites, attempted to recreate Adam's state of innocence before the Fall. They practiced sacred nudity during religious gatherings as a symbol of rejecting social conventions and achieving total liberation from original sin.
• Adamite — A person belonging to an early or medieval Christian religious sect that preached a return to the paradisiacal innocence of Adam before the commission of original sin. As an adjective, the term describes the followers or characteristics of this radical ascetic movement, renowned for practicing ritual nudism and completely rejecting social institutions, private property, and clothing during secret gatherings.
• Adoptionists — Members, adherents, or promoters of the doctrine of adoptionism, who denied the inherent and eternal divinity of Jesus Christ, arguing that his status as Son of God was achieved through divine adoption at his baptism. The term is used strictly in ecclesiastical historiography to denote religious factions of antiquity and the early Middle Ages in conflict with trinitarian orthodoxy.
• Aeken — The historical, archaic, or old Flemish/Dutch dialectal name for the city of Aachen (located in present-day Germany, near the borders with Belgium and the Netherlands). The term is found in medieval documents, old chronicles, and European historiography to designate the ancient residence capital of Charlemagne and the historic coronation site of German kings.
• Aga — A regional form or old phonetic variant of the noun 'agă', denoting an administrative and military title granted to certain commanders in the Ottoman Empire or, in the Romanian Principalities, to the boyar who headed the capital's police (agía). In rural or Balkan contexts, the term survives as a lexical archaism used to indicate a local authority figure or official.
• Aga — A regional form or old phonetic variant of the noun 'agă'; an administrative and military title granted in the Ottoman Empire, also adopted in the Romanian Principalities to designate the boyar who headed the agia and held the leadership duties of the capital's police. The person with this rank had the role of ensuring public order, guarding towns, and enforcing medieval administrative directives.
• Alai-bash-chaush — An old honorary title or administrative-military office of Ottoman origin from the medieval period of the Romanian Principalities, designating the chief or commander of the 'ceauși' (couriers, ushers, or bodyguards) who led and maintained order within official princely retinues or processions. This dignitary held the structural role of preserving court discipline during major public ceremonies.
• Alaric — The name borne by famous Visigothic kings, most notably Alaric I (c. 370–410 AD), the first Germanic leader to besiege and sack Rome in August 410 AD, an event of devastating psychological and political impact that symbolically marked the irreversible decline of the Western Roman Empire. His structural and military persona dominated the Migration Period, being renowned for his strategic abilities and for securing broad territorial concessions from imperial authorities.
• Alboin — A proper name of Germanic origin borne by the famous king of the Lombards in the 6th century (c. 560–572), who led his people's massive migration into the Italian Peninsula and laid the foundations of the Lombard Kingdom by conquering vast Byzantine territories.
• Alchemy — A mystical and hermetic science and doctrine that preceded modern chemistry, widely practiced in Antiquity and the Middle Ages, with the primary objectives of transmuting base metals into gold or silver, discovering a universal panacea, and obtaining the Philosopher's Stone. In a metaphorical sense, it denotes a profound, mysterious transformation or a perfect fusion between abstract elements, feelings, or ideas.
• Alchemist — A person who practiced alchemy in Antiquity or the Middle Ages, engaging in secret laboratory experiments to transmute metals and discover the elixir of life; a precursor to the modern chemist. As an adjective, it describes a person or action reminiscent of the occult techniques or mysterious transformations specific to these scholars.
• Alexandrie — An archaic literary term used to designate a popular tale, chronicle, or medieval chivalric romance recounting the life, heroic deeds, and legendary military campaigns of Alexander the Great. It originates from the tradition of old Romanian manuscripts and defines a specific narrative genre blending historical truth with mythological and fantastic elements.
• Archaic alchemist — An old, archaic, or regional phonetic variant for alchemist; a person from the Middle Ages or Renaissance who practiced alchemy, seeking the transmutation of base metals into gold or silver via the philosopher's stone. In ancient literature, it described court scholars manipulating primitive chemicals.
• Amadis of Gaul — A masterpiece of medieval and Renaissance Spanish literature, representing the most famous and influential chivalric romance in the Castilian language; rewritten and published in 1508 by Garci Rodríguez de Montalvo. The work follows the fantastic adventures, heroic deeds, and idealized love of the knight-errant Amadis.
• Amalasuntha — A prominent historical figure of Late Antiquity, serving as the regent queen of the Ostrogoths (526–534) and later queen regnant (534–535); daughter of Theodoric the Great. Famous for her high education and pro-Byzantine policy, her assassination triggered Justinian's invasion of Italy.
• Annate — A historical ecclesiastical tax or fee, specific to the Western Middle Ages, representing the first year's income of a newly assigned church benefice or parish, which had to be paid directly to the Papal See or the local bishop. This structural financial obligation constituted a major source of revenue for the pontifical treasury and generated heated political disputes between European monarchies and the authority in Rome.