Twelve (12). Used, as an alternate word, by those who wish to rid the English-speaking number
system of remnants of an extinct base-12 number
system and de-anomalise the ubiquitous base-10 (decimal)
system.
See firsteen
"Seconteen months hath one year", quoth Wittingstein. "And
twice seconteen maketh one
day", addeth Kant. "Of that we can both be
sure!"