Definition of millennian in US English:

millennian

noun

  • Millenarianrare.

adjective

  • Of, relating to, or characteristic of a period in which one millennium ends and another begins, especially to associated feelings of expectation or apprehension and their cultural manifestations.

Origin

Late 17th century; earliest use found in Millennianism. From post-classical Latin millennium millennium + -an.

Pronunciation

millennian

/mɪˈlɛnɪən/