n. & adj.
n. 1 the position in a sequence corresponding to the number 12 in the sequence 1-12. 2 something occupying this position. 3 each of twelve equal parts of a thing. 4 Mus. a an interval or chord spanning an octave and a fifth in the diatonic scale. b a note separated from another by this interval.
adj. that is the twelfth. Twelfth Day 6 Jan., the twelfth day after Christmas, the festival of the Epiphany. twelfth man a reserve member of a cricket team. Twelfth Night the evening of 5 Jan., the eve of the Epiphany. twelfth part = sense 3 of n. twelfthly adv.
[ OE twelfta (as TWELVE) ]