Consisting of or continuing for seven years.(adjective)
An event that occurs every seven years.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "septennial" in a sentence
"Elections had become a cheerful formality, a septennial folly, an ancient unmeaning custom; a social Parliament as ineffectual as the convocation of the Established Church in"
"Yet candour will own that to the same parliament every Englishman is deeply indebted: the septennial act, so vicious in its origin, has been sanctioned by time, experience, and the national consent."
"The first parliament of George the First had been chosen (1715) for three years: the term had elapsed, their trust was expired; and the four additional years (1718-1722), during which they continued to sit, were derived not from the people, but from themselves; from the strong measure of the septennial bill, which can only be paralleled by il serar di consiglio of the Venetian history."