Short answers, pulled from the story.
Medieval Latin served as the primary written language of scholarship, law, administration, and the Roman Catholic Church across Latin Christendom. It functioned as a lingua franca for educated elites, enabling long-distance correspondence across political borders. Its users included theologians, lawyers, chroniclers, and court officials.
Medieval Latin absorbed vocabulary from Greek, Hebrew, and Germanic languages, and its grammar drifted toward the patterns of authors' native tongues. Word order shifted from the classical Subject-Object-Verb preference toward Subject-Verb-Object, articles appeared where Classical Latin had none, and new conjunctions replaced older indirect-discourse constructions. Spelling also changed substantially, with diphthongs like ae collapsing to a plain e.
Scholars disagree on the exact boundaries. Some place the start as early as the rise of Ecclesiastical Latin in the middle of the 4th century, others around 500, and others around 900 when Romance languages began replacing written Latin in many regions. Medieval Latin was eventually superseded by humanist Renaissance Latin, known as Neo-Latin.
Key figures include Boethius (c. 480-524), who translated Aristotle and wrote De consolatione Philosophiae; Isidore of Seville (c. 560-636), who compiled the Etymologiae; Bede (c. 672-735), who wrote the Ecclesiastical History of the English People; and Thomas Aquinas (c. 1225-1274), whose Summa Theologiae remains a landmark of medieval thought. Alcuin (c. 735-804) played a central role in the Carolingian Renaissance as Charlemagne's Latin secretary.
The Carolingian Renaissance, kindled under the patronage of Charlemagne, king of the Franks, marked the high point of Medieval Latin as a literary language. Alcuin, serving as Charlemagne's Latin secretary, helped revive Latin literature and learning after the decline that followed the collapse of Western Roman authority. The reforms of the 9th century also introduced Carolingian minuscule script, which standardized the visual appearance of Latin manuscripts.
Many common English abstract terms derive from meanings assigned to them in Medieval Latin. Words like abstract, subject, communicate, matter, and probable carry the senses that medieval scholars gave them, often as newly coined terms for concepts that had no direct equivalent in earlier European languages.