From WordNet (r) 2.0 (August 2003) [wn]:
steed
n : (literary) a spirited horse for state or war
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Steed \Steed\ (st[=e]d), n. [OE. stede, AS. st[=e]da a
stud-horse, war horse, fr. st[=o]d a stud of breeding steeds;
akin to G. stute a mare, Icel. stedda, st[=o][eth], a stud.
[root]163. See Stud of horses.]
A horse, especially a spirited horse for state or war; --
used chiefly in poetry or stately prose. "A knight upon a
steed." --Chaucer.
[1913 Webster]
Mounted upon a hot and fiery steed. --Shak.
[1913 Webster]