Dictionary 1. (n.) A period of ten years.2. (n.) A tithing consisting of ten neighboring families. Thesaurus abundant year academic year bissextile year calendar month calendar year century common year day decade decennary decennium defective year fiscal year fortnight hour leap year lunar month lunar year lunation luster lustrum man-hour microsecond millennium millisecond minute moment month moon quarter quinquennium regular year second semester session sidereal year solar year sun term trimester twelvemonth week weekday year |