bimillennial

adjective

1. of or relating to a bimillennium.

noun, plural bi·mil·le·nar·ies.

2. bimillennium.

noun, plural bi·mil·len·ni·ums, bi·mil·len·ni·a [bahy-mi-len-ee-uh] /ˌbaɪ mɪˈlɛn i ə/.

1. a period of two thousand years.
2. a two thousandth anniversary.

adjective

1. marking a two-thousandth anniversary

noun plural -naries

2. a two-thousandth anniversary