treize

Treize is the French word for the cardinal number 13. It is used in counting, in dates, quantities, and in forming ordinals, such as treizième for 13th. In the 24-hour clock, phrases like treize heures denote 1:00 PM. The number is invariable with gender when used as an adjective before nouns (treize personnes, treize filles, treize voitures).

Etymology and form: the modern French treize derives from Latin tredecim, via Old French treze. The spelling and pronunciation reflect classical Latin roots, with the final -e and the soft z sound typical of French numerals.

In mathematics, treize is notable for several properties. It is a prime number, the sixth prime (2, 3, 5, 7, 11, 13). It is also a Fibonacci number (the seventh term in the sequence 1, 1, 2, 3, 5, 8, 13, …). In base-10 numerals it is written as 13, and in many locales the number is associated with various cultural references and traditions.

Cultural associations: in many Western contexts, the number 13 is regarded as unlucky, a concept often described as triskaidekaphobia in English. In French, as in other languages, the day Friday the 13th is a common motif in folklore and popular culture. Despite superstition, 13 also appears in everyday contexts such as addresses, room numbers, and product naming.

See also: French numerals, lists of numbers in French, and common mathematical properties of small primes.