sexennate
/sɛkˈsɛneɪt/ /sɛkˈsɛnɪt/noun
A period of six years. Chiefly (with capital initial) with reference to a German parliamentary act of 10 April 1898 permitting the creation of a restricted naval fleet over a six-year period.
Origin
Late 19th century; earliest use found in The Times. From sexennis after an interval of six years + -ate, after septennate.