c. 1400, from horse (n.) + tail (n.). As a kind of plant, from 1530s.
horsepower
horse-race
horseradish
horse-shit
horseshoe
horsetail
horse-whip
horsewoman
horst
Horst Wessel
horsy
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}