from
The Collaborative International Dictionary of English v.0.48
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said of certain vehicles in which horse power has been
replaced by electricity, steam, etc.; as, a horseless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]