n. age, era, length of time; time

Huzrah nu, kul do od, wah aan bok lingrah vod, Ahrk fin tey, boziik fun, do fin gein!
Hearken now, sons of snow, to an age, long ago, and the tale, boldly told, of the one!
(Book, Songs of Skyrim)

A period or length of time, or a moment in time. Not the age of a person or thing.

May derive from bo ‘to fly/flow’ in the sense of ‘a flight/flow of time’.