מְתֻמָּן (metumán) — octagon

Etymology

The word מְתֻמָּן belongs to a family of Hebrew polygon names whose history runs from medieval Spain to 20th-century Palestine. The underlying system — forming the name of each polygon from its number of sides — was established by the Catalan-Jewish scholar Abraham bar Hiyya (Abraham Savasorda) in his geometry textbook Ḥibbur ha-Meshiḥa veha-Tishboret (c. 1116), the first major Hebrew geometry text. Bar Hiyya wrote the book to serve Jewish communities in France who had no access to scientific works in their language. He named the triangle מְשֻׁלָּשׁ (three-sided), the square מְרֻבָּע (four-sided), the pentagon מְחֻמָּשׁ (five-sided), the hexagon מְשֻׁשָּׁה or מְשֻׁשֶּׁת, and the octagon מְשֻׁמָּן — all derived from the Hebrew number words with the mefual (מְפֻעָּל) passive participle pattern.

Bar Hiyya also coined מְעֻיָּן (rhombus/diamond shape) based on the Arabic muʿayyan (defined, marked), which itself translated the Greek pleuron (rib/side). This system was used in subsequent Hebrew geometry texts, including the translation of Euclid's Elements by Moses ibn Tibbon in 13th-century Spain, and in Baruch ben Jacob of Shklov's 1780 translation made at the instruction of the Vilna Gaon.

When the 20th century required modern geometry textbooks for Palestine's young Hebrew schools, Yitzhak Ladizhensky published Geometry: A Systematic Course for Secondary Schools in 1920. He used most of Bar Hiyya's terminology and coined מְצֻלָּע (polygon, literally "many-sided") and מַלְבֵּן (rectangle, giving new meaning to an old synonym for "brick"). The Hebrew Language Committee accepted most of Ladizhensky's terms in the 1930s with two notable changes: the Greek-derived trapezoid term was Hebraized to טְרַפֵּז, and מְשֻׁמָּן for octagon was replaced with מְתֻמָּן. The reason for the change was practical: מְשֻׁמָּן already existed in Hebrew with the meaning "fattened" (from שֶׁמֶן, oil/fat), and the homonymy was confusing. To resolve this, the Committee substituted the Aramaic word for eight — תְּמָנְיָא — giving the clean, unambiguous מְתֻמָּן.

Key Quotes

"והשטח המרבה צלעים נחלק למינים מהם מחומש... ומהם משושת... וכן המשובע והמשומן, כל אחד מהם שמו חצוב מן מנין צלעותיו" — אברהם בר חייא, חיבור המשיחה והתשבורת, ~1116

Timeline

• ~1116: Abraham bar Hiyya creates the polygon naming system in Spain; octagon is מְשֻׁמָּן
• ~1240s: Moses ibn Tibbon translates Euclid's Elements into Hebrew in Spain; uses Bar Hiyya's terms
• 1780: Baruch ben Jacob of Shklov translates Euclid in Holland at direction of Vilna Gaon; adds מַקְבִּילִית (parallelogram)
• 1920: Yitzhak Ladizhensky publishes first systematic Hebrew geometry textbook; coins מְצֻלָּע and מַלְבֵּן
• 1930s: Hebrew Language Committee replaces מְשֻׁמָּן with מְתֻמָּן to avoid confusion with "fattened"
• Present: מְתֻמָּן standard in Israeli mathematics education

Related Words

• מְשֻׁלָּשׁ — triangle (three-sided)
• מְרֻבָּע — square (four-sided)
• מְחֻמָּשׁ — pentagon (five-sided)
• מְשֻׁשֶּׁה — hexagon (six-sided)
• מְשֻׁבָּע — heptagon (seven-sided)
• מְצֻלָּע — polygon (coined by Ladizhensky, 1920)
• מַלְבֵּן — rectangle (revived by Ladizhensky, 1920)
• מְעֻיָּן — rhombus (coined by Bar Hiyya from Arabic)
• טְרַפֵּז — trapezoid (from Greek trapezion, "small table")