billennial

But Dr. Niebuhr has gone beyond all that, and the "soaring of his soul" into millennial, billennial, and even trillennial prophecy seems to have boundless possibilities.

1934, Edith Abbott, Sophonisba Preston Breckinridge, The Social Service Review, page 383

While the lack of privacy was precisely what made Ballard's billennial city, Harrison's New York, Hersey's New Haven, and Silverberg's urban monads so horrific, the citizens of Brin's global society rejoice in the disappearance of an informational privacy that they have come to regard as nothing more than a protection for the privileges of the affluent (e.g. Swiss bank accounts) or a cloak for unlawful maneuvers of governmental and corporate institutions.

2008, Ursula K. Heise, Sense of Place and Sense of Planet, →ISBN

Even now, the first tentative exploration in force of the Andromeda Galaxy are producing a ripple of expansion thence—among those political entities with the leisure for intergalactic expansion and the naïveté to believe they can hold empires together across that billennial void.

2014, Dave Van Arnam, Star Barbarian, →ISBN, page 4