a. 无马的, 不用马的

Horseless \Horse"less\, a.
Being without a horse; specif., not requiring a horse; --
said of certain vehicles in which horse power has been
replaced by electricity, steam, etc.; as, a horseless
carriage or truck. It was used primarily in the term
``horseless carriage'', to refer to automobiles. By the
1930's when automobiles had become more common than horses
for transportation, the term had lost its currency. [archaic,
except in a historical context.]
[Webster 1913 Suppl. +PJC]