noun - was a member of the highest
rank of the feudal Bulgarian, Romanian, and
Russian aristocracy, second only to the ruling princes, from the 10th century through the 17th century.
As well, represented as a kick-ass melee/missle cavalry unit useable in the Medieval Total
War games when playing as (mainly) the Russian faction.
Boyars weren't exactly the Eastern equivalent of Western knights, but they were close.
While playing in an online
battle of Medieval Total
War, Chris decimated the rear ranks of his oppoinents' spearmen by cavalry rushing with
two units of Boyars.