n. & adj.
n. 1 one more than eleven; the product of two units and six units. 2 a symbol for this (12, xii, XII). 3 a size etc. denoted by twelve. 4 the time denoted by twelve o'clock (is it twelve yet?). 5 (the Twelve) the twelve apostles. 6 (12) Brit. (of films) classified as suitable for persons of 12 years and over.
adj. that amount to twelve. twelve-note (or -tone) Mus. using the twelve chromatic notes of the octave on an equal basis without dependence on a key system.
[ OE twelf(e) f. Gmc, prob. rel. to TWO ]