Dozen
Part of speech: noun
Definition: A set of twelve. A large, unspecified number of, comfortably estimated in small multiples of twelve, thus generally implied to be significantly more than ten or twelve, but less than perhaps one or two hundred; many. An old English measure of ore containing 12 hundredweight.
Example sentence: Heartthrobs are a dime a dozen.
Twelve
Part of speech: numeral
Definition: The cardinal number occurring after eleven and before thirteen, represented in Roman numerals as XII and in Arabic numerals as 12.
Part of speech: noun
Definition: A group of twelve items.
Example sentence: A jury is composed of twelve men of average ignorance.