n. The number ten; in a Pythagorean or cabalistic sense, as an element of the universe, the tetractys or quaternary number.n. A set of ten objects; ten considered as a whole or unit.n. Specifically A period of ten consecutive years.n. In music, a group of ten tones, having precise acoustical relations with one another, arranged so as to explain and correct problems in harmony and modulation.n. A division of a literary work containing ten parts or books.n. Same as decad ring.