Meaning

noun the cardinal number that is the sum of eleven and one

adjective denoting a quantity consisting of 12 items or units

originFrom Middle English twelve, from Old English twelf (“twelve”), from Proto-Germanic *twalif, an old compound of *twa- (“two”) and *-lif (“left over”) (i.e., two left over after having already counted to ten), from Proto-Indo-European *leyp- (“leave, remain”). Cognate with Saterland Frisian tweelf, tweelif, tweelich (“twelve”), West Frisian tolve (“twelve”), Dutch twaalf (“twelve”), German Low…

Etymology from Wiktionary, CC BY-SA 3.0