Webster's Revised Unabridged Dictionary · 1913

Millenary

Millenary , adjective

[Latin millenarius, from milleni a thousand each, from mille a thousand: compare French millénaire. See Mile.]

Consisting of a thousand; millennial.

Millenary , noun

The space of a thousand years; a millennium; also, a Millenarian.
During that millenary. — Hare