Short answers, pulled from the story.
Hesychius of Alexandria was a Greek grammarian who lived in the 5th or 6th century AD. He compiled a massive collection of words that survives today as the richest lexicon of obscure Greek terms ever found.
The work is titled Alphabetical Collection of All Words and contains more than 50,000 entries explaining meaning alongside references to specific authors. Many words appear only in this single surviving document and nowhere else in ancient literature.
A deeply corrupt 15th-century manuscript holds the only surviving copy of the complete work and resides in the Library of Saint Mark at Venice under catalog number Marc. Gr. 622. No other copies of the entire work have been discovered by scholars to date.
Modern editions include four volumes with volume one published in 1953 and volume two following posthumously in 1966 after Kurt Latte's death. Peter Allan Hansen and Ian C. Cunningham completed volumes three and four in 2005 and 2009 respectively.
The text preserves evidence for obscure Balkan dialects such as Albanoid and Thracian languages that appear nowhere else in surviving ancient Greek literature outside this specific collection. Linguists rely on these unique entries to map out extinct linguistic families across the Balkans.