| BIENNIALLY | • biennially adv. Taking place every two years. • BIENNIAL adv. occurring every two years. |
| CENTENNIALLY | • centennially adv. As part of a centennial. • centennially adv. Once a century, every one hundred years. • CENTENNIAL adv. recurring every hundred years; lasting a hundred years. |
| DECENNIALLY | • decennially adv. Every ten years. • DECENNIAL adv. happening every ten years. |
| MILLENNIALLY | • millennially adv. In millennial terms. • MILLENNIAL adv. of or relating to a millennium. |
| OCTENNIALLY | • octennially adv. Every eight years. • OCTENNIAL adv. recurring every eighth year. |
| PERENNIALLY | • perennially adv. Year after year (literally: each year). • perennially adv. Constantly; with frequent recurrence. • PERENNIAL adv. lasting for many years. |
| PREMILLENNIALLY | • premillennially adv. Before the millennium. • PREMILLENNIAL adv. coming before a millennium. |
| QUADRENNIALLY | • quadrennially adv. Every four years. • QUADRENNIAL adv. lasting four years; occurring once every four years. |
| QUINQUENNIALLY | • quinquennially adv. Every five years. • QUINQUENNIAL adv. lasting five years; occurring every fifth year. |
| SEPTENNIALLY | • septennially adv. Once in every seven years. • SEPTENNIAL adv. lasting or continuing seven years; as, septennial parliaments. |
| SEXENNIALLY | • sexennially adv. Once in every six years. • SEXENNIAL adv. lasting six years, or happening once in six years. |
| TRIENNIALLY | • triennially adv. Occurring at intervals three years apart. • TRIENNIAL adv. continuing for three years. |