What does duodecimal mean?
Duodecimal describes anything based on or expressed in the number twelve, most often referring to a positional numeral system that uses twelve as its base rather than the familiar base-ten (decimal) system. As an adjective it modifies nouns such as system, notation, arithmetic, or fraction; as a noun it can denote either a number written in base twelve or the base-twelve system itself. Because twelve is divisible by two, three, four, and six, advocates of duodecimal arithmetic point out that fractions like one-third are represented exactly, without the repeating decimals that plague base ten. Traces of twelve-based thinking survive throughout everyday life: the clock's twelve hours, twelve inches to the foot, and dozens as units of counting all reflect humanity's long familiarity with grouping by twelves. Though rarely encountered outside mathematics and historical discussions of measurement, duodecimal remains a precise, well-established technical word.
Based on, relating to, or expressed in the number twelve; denoting a numeral system with twelve as its base.
"Clock faces preserve a duodecimal division of the day into twelve hours."
The dominant form of the word in modern usage.
A number expressed in base twelve, or the base-twelve numeral system itself.
"Written in duodecimal, the quantity we call thirty-six is rendered as 30."
Used when referring to individual numbers written in base twelve.
"The table lists several common fractions as duodecimals."
The Babylonians and ancient Romans both leaned on twelve rather than ten — which is why we still have 12 hours on a clock face, 12 inches in a foot, and 12 items in a dozen.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of duodecimal
Duodecimal derives from Latin duodecimus, meaning 'twelfth', formed from duo ('two') plus decimus ('tenth'), from decem ('ten'). It entered English in the mid-seventeenth century alongside other learned Latin numerical borrowings such as decimal. Its closest relatives include dozen (from Old French dozeine, ultimately from Latin duodecima) and decimal (from Latin decimalis, from decimus).
Related word forms
How duodecimal is actually used
A technical term used chiefly in mathematics, metrology, and discussions of numeral systems. The adjective use is far more common than the noun. It carries no emotional connotation and appears almost exclusively in formal or specialist writing.
Easily confused with duodecimal
Decimal is based on ten (the standard system of everyday arithmetic), whereas duodecimal is based on twelve.