Consisting of, or lasting for, seven years.

Continuing for, or covering a period of, five years; holding office for five years.

Existing or lasting for three years, three-years'; changed every three years.

Lasting seven years; recurring every seven years. Also more generally: based on or relating to the number seven.

Existing or lasting for two years; changed every two years.

Lasting seven years; taking seven years to build. Obsolete.

Lasting seven years; spec. (British History) with reference or allusion to the Septennial Act (cf. Septennial Act n. at compounds).

= biennial, adj.

Lasting for or relating to a period of four years.

Made triennial. (In quot. 1661, as the second element of a compound.)

Used to form nouns and adjectives with the sense ‘relating to, consisting of, or having five (of the thing specified)’, as quintagenarian, quintopoly…

lasting 500 years.