"metal device fixed to the outside of a door for banging to give notice when someone desires admission," 1794, from door + knocker (n.).
doom
doomsday
door
door-bell
door-knob
door-knocker
door-mat
doornail
doorstep
door-stop
door-strip
)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}